Kaifeng, known by several names, is a prefecture-level city in east-central Henan province, China. It is one of the Eight Ancient Capitals of China, for being the capital seven times in history, is most famous for being the capital of China in the Northern Song dynasty. There are about 5 million people living in its metropolitan area. Located along the southern bank of the Yellow River, it borders the provincial capital of Zhengzhou to the west, Xinxiang to the northwest, Shangqiu to the east, Zhoukou to the southeast, Xuchang to the southwest, Heze of Shandong to the northeast; the postal romanization for the city is "Kaifeng". Its official one-character abbreviation in Chinese is 汴, it has been known as Dàliáng Biànliáng Biànzhōu Nánjīng Dōngjīng Biànjīng The name "Kaifeng" first appeared as the area's name after the Qin's conquest of China in the second century BC and means "expand the borders" and figuratively "hidden" and "vengeance". Its name was Qifeng, but the syllable qi was changed to the synonymous kai （/*Nə-ʰˤəj/, /*ʰˤəj/） to avoid the naming taboo of Liu Qi.
The prefecture-level city of Kaifeng administers five districts and four counties: Gulou District Longting District Yuwangtai District Xiangfu District Shunhe Hui District Weishi County Qi County Tongxu County Lankao County Kaifeng is one of the Eight Ancient Capitals of China. As with Beijing, there have been many reconstructions during its history. In 364 BC during the Warring States period, the State of Wei founded a city called Daliang as its capital in this area. During this period, the first of many canals in the area was constructed linking a local river to the Yellow River; when the State of Wei was conquered by the State of Qin, Kaifeng was destroyed and abandoned except for a mid-sized market town, which remained in place. Early in the 7th century, Kaifeng was transformed into a major commercial hub when it was connected to the Grand Canal as well as through the construction of a canal running to western Shandong. In 781 during the Tang dynasty, a new city was named Bian. Bian was the capital of the Later Jin, Later Han, Later Zhou of the Five Dynasties and Ten Kingdoms period.
The Song dynasty made Bian its capital when it overthrew the Later Zhou in 960. Shortly afterwards, the city underwent further expansion. During the Song, when it was known as Dongjing or Bianjing, Kaifeng was the capital, with a population of over 400,000 living both inside and outside the city wall. Typhus was an acute problem in the city; the historian Jacques Gernet provides a lively picture of life in this period in his Daily Life in China on the Eve of the Mongol Invasion, 1250-1276, which draws on Dongjing Meng Hua Lu, a nostalgic memoir of the city of Kaifeng. In 1049, the Youguosi Pagoda – or Iron Pagoda as it is called today – was constructed measuring 54.7 metres in height. It has survived the vicissitudes of war and floods to become the oldest landmark in this ancient city. Another Song-dynasty pagoda, Po Tower, dating from 974, has been destroyed. Another well-known sight was the astronomical clock tower of the engineer and statesman Su Song, it was crowned with a rotating armillary sphere, hydraulically-powered, yet it incorporated an escapement mechanism two hundred years before they were found in the clockworks of Europe and featured the first known endless power-transmitting chain drive.
Kaifeng reached its peak importance in the 11th century when it was a commercial and industrial center at the intersection of four major canals. During this time, the city was surrounded by three rings of city walls and had a population of between 600,000 and 700,000, it is believed that Kaifeng was the largest city in the world from 1013 to 1127. This period ended in 1127, it subsequently came under the rule of the Jurchen Jin dynasty, which had conquered most of North China during the Jin–Song Wars. While it remained an important administrative center, only the city area inside the inner city wall of the early Song remained settled and the two outer rings were abandoned. One major problem associated with Kaifeng as the imperial capital of the Song was its location. While it was conveniently situated along the Grand Canal for logistic supply, Kaifeng was militarily vulnerable due to its position on the floodplains of the Yellow River. Kaifeng was reconstructed during this time; the Jurchen kept their main capital further north until 1214 when they were forced to move the imperial court southwards to Kaifeng in order to flee from the onslaught of the Mongols.
In 1232 they succumbed to the combined Song forces in the Mongol siege of Kaifeng. The Mongols captured the city, in 1279 they conquered all of China. At the beginning of the Ming dynasty in 1368, Kaifeng was made the capital of Henan province. In 1642, Kaifeng was flooded by the Ming army with water from the Yellow River to prevent the peasant rebel Li Zicheng from taking over. After this disaster, the city was abandoned again. In 1662, during the reign of the Kangxi Emperor in the Qing dynasty, Kaifeng was rebuilt. However, further flooding occurred in 1841 followed by another reconstruction in 1843, which produced the contemporary Kaifeng as it stands today. On 6 June 1938, the city was occupied by the invading Japanese Imperial Army. Kaifeng is also
Luoyang is a city located in the confluence area of Luo River and Yellow River in the west of Henan province. Governed as a prefecture-level city, it borders the provincial capital of Zhengzhou to the east, Pingdingshan to the southeast, Nanyang to the south, Sanmenxia to the west, Jiyuan to the north, Jiaozuo to the northeast; as of the final 2010 census, Luoyang had a population of 6,549,941 inhabitants with 1,857,003 people living in the built-up area made of the city's five urban districts, all of which except the Jili District are not urbanized yet. Situated on the central plain of China, Luoyang is one of the cradles of Chinese civilization, is one of the Four Great Ancient Capitals of China; the name "Luoyang" originates from sunny side of the Luo River. Since the river flows from west to east and the sun is to the south of the river, the sun always shines on the north side of the river. Luoyang has had several names over the centuries, including "Luoyi" and "Luozhou", though Luoyang has been its primary name.
It has been called, during various periods, "Dongdu", "Xijing", or "Jingluo". During the rule of Wu Zetian, the city was known as Shendu The greater Luoyang area has been sacred ground since the late Neolithic period; this area at the intersection of the Luo river and Yi River was considered to be the geographical center of China. Because of this sacred aspect, several cities – all of which are referred to as "Luoyang" – have been built in this area. In 2070 BC, the Xia dynasty king Tai Kang moved the Xia capital to the intersection of the Luo and Yi and named the city Zhenxun. In 1600 BC, Tang of Shang defeated Jie, the final Xia dynasty king, built Western Bo, a new capital on the Luo River; the ruins of Western Bo are located in Luoyang Prefecture. In the 1036 BC a settlement named Chengzhou was constructed by the Duke of Zhou for the remnants of the captured Shang nobility; the Duke moved the Nine Tripod Cauldrons to Chengzhou from the Zhou dynasty capital at Haojing. A second Western Zhou capital, Wangcheng was built 15 km west of Chengzhou.
Wangcheng became the capital of the Eastern Zhou Dynasty in 771 BC. The Eastern Zhou Dynasty capital was moved to Chengzhou in 510 BC; the Eastern Han Dynasty capital of Luoyang would be built over Chengzhou. Modern Luoyang is built over the ruins of Wangcheng, which are still visible today at Wangcheng Park. In 25 AD, Luoyang was declared the capital of the Eastern Han Dynasty on November 27 by Emperor Guangwu of Han. For several centuries, Luoyang was the focal point of China. In AD 68, the White Horse Temple, the first Buddhist temple in China, was founded in Luoyang; the temple still exists, though the architecture is of origin from the 16th century. An Shigao was one of the first monks to popularize Buddhism in Luoyang; the ambassador Banchao restored the Silk Road in Eastern Han dynasty and this has made the capital city Luoyang the start of Silk Road In 166 AD, the first Roman mission, sent by "the king of Da Qin, Andun", reached Luoyang after arriving by sea in Rinan Commandery in what is now central Vietnam.
The late 2nd century saw China decline into anarchy: The decline was accelerated by the rebellion of the Yellow Turbans, although defeated by the Imperial troops in 184 AD, weakened the state to the point where there was a continuing series of rebellions degenerating into civil war, culminating in the burning of the Han capital of Luoyang on 24 September 189 AD. This was followed by a state of continual unrest and wars in China until a modicum of stability returned in the 220s, but with the establishment of three separate kingdoms, rather than a unified empire. In 190 AD, Chancellor Dong Zhuo ordered his soldiers to ransack and raze the city as he retreated from the coalition set up against him by regional lords all across China; the court was subsequently moved to the more defensible western city of Chang'an. Following a period of disorder, during which warlord Cao Cao held the last Han emperor Xian in Xuchang, Luoyang was restored to prominence when his son Cao Pi, Emperor Wen of the Wei dynasty, declared it his capital in 220 AD.
The Jin dynasty, successor to Wei, was established in Luoyang. When Jin was overrun by Xiongnu forces in 311 AD, it was forced to move its capital to Jiankang; the Xiongnu warriors sacked and nearly destroyed Luoyang. The same fate befell Chang'an in 316 AD. In winter 416, Luoyang fell to Liu Yu's general Tan Daoji. In 422, Luoyang was captured by Northern Wei. Liu Song general Dao Yanzhi took the city back. In 493 AD, Emperor Xiaowen of the Northern Wei dynasty moved the capital from Datong to Luoyang and started the construction of the rock-cut Longmen Grottoes. More than 30,000 Buddhist statues from the time of this dynasty have been found in the caves. Many of these sculptures were two-faced. At the same time, the Shaolin Temple was built by the Emperor to accommodate an Indian monk on the Mont Song right next to Luoyang City; the Yongning Temple, the tallest pagoda in China, was built in Luoyang. When Emperor Yang of Sui took control in 604 AD he founded the new Luoyang on the site of the existing city using a layout inspired by his father Emperor Wen of Sui's work in newly rebuilt Chang'an.
During the Tang dynasty, Luoyang was Dongdu, the "Eastern Capital", at its height had a population of around one million, second only to Chang'an, which, at the t
A quadrant is an instrument, used to measure angles up to 90°. Different versions of this instrument could be used to calculate various readings, such as longitude and time of day, it was proposed by Ptolemy as a better kind of astrolabe. Several different variations of the instrument were produced by medieval Muslim astronomers; the term “quadrant”, meaning one fourth, refers to the fact that early versions of the instrument were derived from astrolabes. The quadrant condensed the workings of the astrolabe into an area one fourth the size of the astrolabe face. One of the earliest accounts of a quadrant comes from Ptolemy's Almagest around AD 150, he described a “plinth” that could measure the altitude of the noon sun by projecting the shadow of a peg on a graduated arc of 90 degrees. This quadrant was unlike versions of the instrument. Ptolemy's version was a derivative of the astrolabe and the purpose of this rudimentary device was to measure the meridian angle of the sun. Islamic astronomers in the Middle Ages improved upon these ideas and constructed quadrants throughout the Middle East, in observatories such as Marageh and Samarkand.
At first these quadrants were very large and stationary, could be rotated to any bearing to give both the altitude and azimuth for any celestial body. As Islamic astronomers made advancements in astronomical theory and observational accuracy they are credited with developing four different types of quadrants during the Middle Ages and beyond; the first of these, the sine quadrant, was invented by Muhammad ibn Musa al-Khwarizmi in the 9th century at the House of Wisdom in Baghdad. The other types were the horary quadrant and the astrolabe quadrant. During the Middle Ages the knowledge of these instruments spread to Europe. In the 13th century Jewish astronomer Jacob ben Machir ibn Tibbon was crucial in further developing the quadrant, he was a skilled astronomer and wrote several volumes on the topic, including an influential book detailing how to build and use an improved version of the quadrant. The quadrant that he invented came to be known as new quadrant; this device was revolutionary because it was the first quadrant to be built that did not involve several moving parts and thus could be much smaller and more portable.
Tibbon's Hebrew manuscripts were translated into Latin and improved upon by French scholar Peter Nightingale several years later. Because of the translation, Tibbon, or Prophatius Judaeus as he was known in Latin, became an influential name in astronomy, his new quadrant was based upon the idea that the stereographic projection that defines a planispheric astrolabe can still work if the astrolabe parts are folded into a single quadrant. The result was a device, far cheaper, easier to use and more portable than a standard astrolabe. Tibbon's work influenced Copernicus, Christopher Clavius and Erasmus Reinhold; as the quadrant became smaller and thus more portable, its value for navigation was soon realized. The first documented use of the quadrant to navigate at sea is by Diogo Gomes. Sailors began by measuring the height of Polaris to ascertain their latitude; this application of quadrants is attributed to Arab sailors who traded along the east coast of Africa and travelled out of sight of land.
It soon became more common to take the height of the sun at a given time due to the fact that Polaris disappears south of the equator. In 1618 English Mathematician Edmund Gunter further adapted the quadrant with an invention that came to be known as the Gunter quadrant; this pocket sized quadrant was revolutionary because it was inscribed with projections of the tropics, the equator, the horizon and the ecliptic. With the correct tables one could use the quadrant to find the time, the date, the length of the day or night, the time of sunrise and sunset and the meridian; the Gunter quadrant was useful but it had its drawbacks. There are several types of quadrants: Mural quadrants, used for determining the time by measuring the altitudes of altitudes of astronomical objects. Tycho Brahe created one of the largest mural quadrants. In order to tell time he would place two clocks next to the quadrant so that he could identify the minutes and seconds in relation to the measurements on the side of the instrument.
Large frame-based instruments used for measuring angular distances between astronomical objects. Geometric quadrant used by navigators. Davis quadrant a compact, framed instrument used by navigators for measuring the altitude of an astronomical object, they can be classified as: Altitude – The plain quadrant with plumb line, used to take the altitude of an object. Gunner's – A type of clinometer used by an artillerist to measure the elevation or depression angle of a gun barrel of a cannon or mortar, both to verify proper firing elevation, to verify the correct alignment of the weapon-mounted fire control devices. Gunter's – A quadrant used for time determination as well as the length of day, when the sun had risen and set, the date, the meridian using scales and curves of the quadrant along with related tables, it was invented by Edmund Gunter in 1623. Gunter's quadrant was simple which allowed for its widespread and long-lasting use in the 17th and 18th centuries. Gunter expanded the basic features of other quadrants to create a convenient and comprehensive instrument.
Its distinguishable feature included projections of the tropics, equator and the horizon. Islamic – King identifi
Kodungallur, is a Municipality on the estuary of River Periyar in Thrissur district, Kerala on the Malabar Coast. It is situated 29 kilometres north of Kochi by National Highway 66. Kodungallur, being a port city at the northern end of the Kerala lagoons, was a strategic entry point for the naval fleets to the extensive Kerala backwaters; as of 2011 India Census, Kodungallur Municipality and Out Growth had a population of 60,190. It had an average literacy rate of 95.10%. Around 64% of the population follows Hinduism, 32% Islam and 4% Christianity. Schedule Caste constitutes 7.8 %. Kodungallur is the headquarters of the Kodungallur sub-district in Thrissur district. Kodungallur Kerala Legislative Assembly constituency is a part of Chalakudi Lok Sabha Constituency. Kodungallur is well connected to other towns in Kerala through road network. Aluva Railway Station in Ernakulam district is the major railway station near Kodungallur. Fort Cranganore, known locally as Kottappuram Fort/Tipu's Fort, was constructed in Kodungallur by Portuguese in 1523.
The fort was enlarged in 1565, passed into the hands of the Dutch in 1663. Thiruvanchikulam Mahadeva Temple, dedicated to god Siva, is one of the major Siva temples in South India. Siva in the Thiruvanchikulam temple was the patron deity of the Chera Perumals of Kerala and remains the family deity of the Cochin Royal Family; the title Kodungallur seems to have derived from the medieval name "Koti Linga Pura". In the medieval period, Kondungallur was part of the city of Makothai Vanchi, it was the seat of the Kerala branch of the Perumals, for about three hundred years. It was known as Muchiri Pattanam, Mahavanchimana Pattanam, Thrikulasekarapuram. Kodungallur was known as Jangli, Cyngilin, Chinkli, Jinkali and Cynkali, which are all derived from the name of the River Changala, a tributary of Periyar. Scholars believe that Muziris, an ancient harbour located on the mouth of Periyar, coincides with modern-day Kodungallur. Central Kerala and Western Tamil Nadu in early historic south India was ruled by the Chera line of rulers.
Recent archaeological excavations seem to confirm the existence of Muziris near Kodungallur. The harbour was visited by navigators from all over the world from the Mediterranean world. Roman Empire had a continuous trading connection with the West Coast of India. Along with spices, commodities such as pearls, ivory, diamonds and perfumes were acquired by the sailors from central Kerala. Traditional belief among the ancient Christians in Kerala is that Apostle St. Thomas landed in or around Kodungallur in the middle of the 1st century CE and founded Seven Churches: Kodungallur, Nilackal, Kottakkavu and Thiruvithamcode Arappally – a "Royal Church". According to one tradition, a Cochin Jew colony in Malabar Coast established before the 6th century BCE, attracted the Apostle to this region; the native Muslim tradition holds that the Cheraman Mosque in Kodungallur, "built in 629 CE by Mālik bin Dīnār", is the oldest mosque in South Asia. The economic and political prestige of harbour of Kodungallur remained in the medieval South India.
Sulaiman, a West Asian visitor to India during this period, recorded the "economic prosperity" of the region. He describes the Chinese traders in the city; the port was sacked by the Chola rulers of neighbouring Tamil Nadu in 11th century CE. After the dissolution of the Chera Perumal rule, Kodungallur emerged as a principality, named Padinjattedathu Swaroopam, under the control of a royal family of Kodungallur Kovilakam; the city state was "allied" either to Calicut. It is postulated that the harbour at Kodungallur was devastated by natural calamities—a flood or an earthquake—in 1341, lost its commercial/strategic importance thereafter; the trade got diverted to other ports of the Malabar Coast, such as Cochin and Calicut. It is speculated that the floods split the left branch of the River Periyar into two, just before the town of Aluva; the flood silted the right branch and the natural harbour at the mouth of the river to make it poorly navigable for large vessels. The Portuguese navigators began operating in South India from early 16th century CE.
During this period, Kodungallur was a "tributary state" of the kingdom of Kozhikode of Zamorins. Since Kodungallur sandwiched between the kingdom of Kozhikode and the kingdom of Kochi, it was a matter of frequent dispute for both the kings; the chieftain of Kodungallur switched the allegiance from one king to another. The Portuguese spice trade was challenged by the kings of Kozhikode in the Indian Ocean; the port of Kodungallur had a sizeable Jewish, native Christian and Muslim population at the time. Portuguese Company extended their aggression on Calicut to allied coastal city-states, including Kodungallur; the port was completely destroyed by the Portuguese on 1 September 1504. Kodungallur, being a port city at the northern end of the Vembanad lagoon, was a strategic entry point for Zamorin's army and fleet into the Kerala backwaters. Hence, in October 1504 Zamorin dispatched a force to fortify Kodungal
The Hellenistic period covers the period of Mediterranean history between the death of Alexander the Great in 323 BC and the emergence of the Roman Empire as signified by the Battle of Actium in 31 BC and the subsequent conquest of Ptolemaic Egypt the following year. The Ancient Greek word Hellas is the original word for Greece, from which the word Hellenistic was derived. At this time, Greek cultural influence and power was at its peak in Europe, North Africa and Western Asia, experiencing prosperity and progress in the arts, literature, architecture, mathematics and science, it is considered a period of transition, sometimes of decadence or degeneration, compared to the enlightenment of the Greek Classical era. The Hellenistic period saw the rise of New Comedy, Alexandrian poetry, the Septuagint and the philosophies of Stoicism and Epicureanism. Greek science was advanced by the works of the polymath Archimedes; the religious sphere expanded to include new gods such as the Greco-Egyptian Serapis, eastern deities such as Attis and Cybele and a syncretism between Hellenistic culture and Buddhism in Bactria and Northwest India.
After Alexander the Great's invasion of the Achaemenid Empire in 330 BC and its disintegration shortly after, the Hellenistic kingdoms were established throughout south-west Asia, north-east Africa and South Asia. The Hellenistic period was characterized by a new wave of Greek colonization which established Greek cities and kingdoms in Asia and Africa; this resulted in the export of Greek culture and language to these new realms, spanning as far as modern-day India. However, these new kingdoms were influenced by the indigenous cultures, adopting local practices where beneficial, necessary, or convenient. Hellenistic culture thus represents a fusion of the Ancient Greek world with that of the Near East, Middle East, Southwest Asia; this mixture gave rise to a common Attic-based Greek dialect, known as Koine Greek, which became the lingua franca through the Hellenistic world. Scholars and historians are divided as to; the Hellenistic period may be seen to end either with the final conquest of the Greek heartlands by Rome in 146 BC following the Achean War, with the final defeat of the Ptolemaic Kingdom at the Battle of Actium in 31 BC, or the move by Roman emperor Constantine the Great of the capital of the Roman Empire to Constantinople in 330 AD.
"Hellenistic" is distinguished from "Hellenic" in that the first encompasses the entire sphere of direct ancient Greek influence, while the latter refers to Greece itself. The word originated from the German term hellenistisch, from Ancient Greek Ἑλληνιστής, from Ἑλλάς. "Hellenistic" is a 19th-century concept. Although words related in form or meaning, e.g. Hellenist, have been attested since ancient times, it was Johann Gustav Droysen in the mid-19th century, who in his classic work Geschichte des Hellenismus, coined the term Hellenistic to refer to and define the period when Greek culture spread in the non-Greek world after Alexander's conquest. Following Droysen and related terms, e.g. Hellenism, have been used in various contexts; the major issue with the term Hellenistic lies in its convenience, as the spread of Greek culture was not the generalized phenomenon that the term implies. Some areas of the conquered world were more affected by Greek influences than others; the term Hellenistic implies that the Greek populations were of majority in the areas in which they settled, but in many cases, the Greek settlers were the minority among the native populations.
The Greek population and the native population did not always mix. While a few fragments exist, there is no complete surviving historical work which dates to the hundred years following Alexander's death; the works of the major Hellenistic historians Hieronymus of Cardia, Duris of Samos and Phylarchus which were used by surviving sources are all lost. The earliest and most credible surviving source for the Hellenistic period is Polybius of Megalopolis, a statesman of the Achaean League until 168 BC when he was forced to go to Rome as a hostage, his Histories grew to a length of forty books, covering the years 220 to 167 BC. The most important source after Polybius is Diodorus Siculus who wrote his Bibliotheca historica between 60 and 30 BC and reproduced some important earlier sources such as Hieronymus, but his account of the Hellenistic period breaks off after the battle of Ipsus. Another important source, Plutarch's Parallel Lives although more preoccupied with issues of personal character and morality, outlines the history of important Hellenistic figures.
Appian of Alexandria wrote a history of the Roman empire that includes information of some Hellenistic kingdoms. Other sources include Justin's epitome of Pompeius Trogus' Historiae Philipicae and a summary of Arrian's Events after Alexander, by Photios I of Constantinople. Lesser supplementary sources include Curtius Rufus, Pausanias and the Byzantine encyclopedia the Suda. In the field of philosophy, Diogenes Laër
Ancient Egypt was a civilization of ancient North Africa, concentrated along the lower reaches of the Nile River in the place, now the country Egypt. Ancient Egyptian civilization followed prehistoric Egypt and coalesced around 3100 BC with the political unification of Upper and Lower Egypt under Menes; the history of ancient Egypt occurred as a series of stable kingdoms, separated by periods of relative instability known as Intermediate Periods: the Old Kingdom of the Early Bronze Age, the Middle Kingdom of the Middle Bronze Age and the New Kingdom of the Late Bronze Age. Egypt reached the pinnacle of its power in the New Kingdom, ruling much of Nubia and a sizable portion of the Near East, after which it entered a period of slow decline. During the course of its history Egypt was invaded or conquered by a number of foreign powers, including the Hyksos, the Libyans, the Nubians, the Assyrians, the Achaemenid Persians, the Macedonians under the command of Alexander the Great; the Greek Ptolemaic Kingdom, formed in the aftermath of Alexander's death, ruled Egypt until 30 BC, under Cleopatra, it fell to the Roman Empire and became a Roman province.
The success of ancient Egyptian civilization came from its ability to adapt to the conditions of the Nile River valley for agriculture. The predictable flooding and controlled irrigation of the fertile valley produced surplus crops, which supported a more dense population, social development and culture. With resources to spare, the administration sponsored mineral exploitation of the valley and surrounding desert regions, the early development of an independent writing system, the organization of collective construction and agricultural projects, trade with surrounding regions, a military intended to assert Egyptian dominance. Motivating and organizing these activities was a bureaucracy of elite scribes, religious leaders, administrators under the control of a pharaoh, who ensured the cooperation and unity of the Egyptian people in the context of an elaborate system of religious beliefs; the many achievements of the ancient Egyptians include the quarrying and construction techniques that supported the building of monumental pyramids and obelisks.
Ancient Egypt has left a lasting legacy. Its art and architecture were copied, its antiquities carried off to far corners of the world, its monumental ruins have inspired the imaginations of writers for centuries. A new-found respect for antiquities and excavations in the early modern period by Europeans and Egyptians led to the scientific investigation of Egyptian civilization and a greater appreciation of its cultural legacy; the Nile has been the lifeline of its region for much of human history. The fertile floodplain of the Nile gave humans the opportunity to develop a settled agricultural economy and a more sophisticated, centralized society that became a cornerstone in the history of human civilization. Nomadic modern human hunter-gatherers began living in the Nile valley through the end of the Middle Pleistocene some 120,000 years ago. By the late Paleolithic period, the arid climate of Northern Africa became hot and dry, forcing the populations of the area to concentrate along the river region.
In Predynastic and Early Dynastic times, the Egyptian climate was much less arid. Large regions of Egypt were traversed by herds of grazing ungulates. Foliage and fauna were far more prolific in all environs and the Nile region supported large populations of waterfowl. Hunting would have been common for Egyptians, this is the period when many animals were first domesticated. By about 5500 BC, small tribes living in the Nile valley had developed into a series of cultures demonstrating firm control of agriculture and animal husbandry, identifiable by their pottery and personal items, such as combs and beads; the largest of these early cultures in upper Egypt was the Badari, which originated in the Western Desert. The Badari was followed by the Amratian and Gerzeh cultures, which brought a number of technological improvements; as early as the Naqada I Period, predynastic Egyptians imported obsidian from Ethiopia, used to shape blades and other objects from flakes. In Naqada II times, early evidence exists of contact with the Near East Canaan and the Byblos coast.
Over a period of about 1,000 years, the Naqada culture developed from a few small farming communities into a powerful civilization whose leaders were in complete control of the people and resources of the Nile valley. Establishing a power center at Nekhen, at Abydos, Naqada III leaders expanded their control of Egypt northwards along the Nile, they traded with Nubia to the south, the oases of the western desert to the west, the cultures of the eastern Mediterranean and Near East to the east, initiating a period of Egypt-Mesopotamia relations. The Naqada culture manufactured a diverse selection of material goods, reflective of the increasing power and wealth of the elite, as well as societal personal-use items, which included combs, small statuary, painted pottery, high quality decorative stone vases, cosmetic palettes, jewelry made of gold and ivory, they developed a ceramic glaze known as faience, used well into the Roman Per
A sundial is a device that tells the time of day when there is sunlight by the apparent position of the Sun in the sky. In the narrowest sense of the word, it consists of a flat plate and a gnomon, which casts a shadow onto the dial; as the Sun appears to move across the sky, the shadow aligns with different hour-lines, which are marked on the dial to indicate the time of day. The style is the time-telling edge of the gnomon, though nodus may be used; the gnomon casts a broad shadow. The gnomon may be wire, or elaborately decorated metal casting; the style must be parallel to the axis of the Earth's rotation for the sundial to be accurate throughout the year. The style's angle from horizontal is equal to the sundial's geographical latitude. In a broader sense, a sundial is any device that uses the Sun's altitude or azimuth to show the time. In addition to their time-telling function, sundials are valued as decorative objects, literary metaphors, objects of mathematical study, it is common for inexpensive, mass-produced decorative sundials to have incorrectly aligned gnomons and hour-lines, which cannot be adjusted to tell correct time.
There are several different types of sundials. Some sundials use a shadow or the edge of a shadow while others use a line or spot of light to indicate the time; the shadow-casting object, known as a gnomon, may be a long thin rod or other object with a sharp tip or a straight edge. Sundials employ many types of gnomon; the gnomon may be moved according to the season. It may be oriented vertically, aligned with the Earth's axis, or oriented in an altogether different direction determined by mathematics. Given that sundials use light to indicate time, a line of light may be formed by allowing the Sun's rays through a thin slit or focusing them through a cylindrical lens. A spot of light may be formed by allowing the Sun's rays to pass through a small hole or by reflecting them from a small circular mirror. Sundials may use many types of surfaces to receive the light or shadow. Planes are the most common surface, but partial spheres, cylinders and other shapes have been used for greater accuracy or beauty.
Sundials differ in their need for orientation. The installation of many dials requires knowing the local latitude, the precise vertical direction, the direction to true North. Portable dials are self-aligning: for example, it may have two dials that operate on different principles, such as a horizontal and analemmatic dial, mounted together on one plate. In these designs, their times agree only. Sundials may indicate the local solar time only. To obtain the national clock time, three corrections are required: The orbit of the Earth is not circular and its rotational axis is not perpendicular to its orbit; the sundial's indicated solar time thus varies from clock time by small amounts that change throughout the year. This correction – which may be as great as 15 minutes – is described by the equation of time. A sophisticated sundial, with a curved style or hour lines, may incorporate this correction; the more usual simpler sundials sometimes have a small plaque that gives the offsets at various times of the year.
The solar time must be corrected for the longitude of the sundial relative to the longitude of the official time zone. For example, an uncorrected sundial located west of Greenwich, England but within the same time-zone, shows an earlier time than the official time, it may show "11:45" at official noon, will show "noon" after the official noon. This correction can be made by rotating the hour-lines by a constant angle equal to the difference in longitudes, which makes this is a possible design option. To adjust for daylight saving time, if applicable, the solar time must additionally be shifted for the official difference; this is a correction that can be done on the dial, i.e. by numbering the hour-lines with two sets of numbers, or by swapping the numbering in some designs. More this is ignored, or mentioned on the plaque with the other corrections, if there is one; the principles of sundials are understood most from the Sun's apparent motion. The Earth rotates on its axis, revolves in an elliptical orbit around the Sun.
An excellent approximation assumes that the Sun revolves around a stationary Earth on the celestial sphere, which rotates every 24 hours about its celestial axis. The celestial axis is the line connecting the celestial poles. Since the celestial axis is aligned with the axis about which the Earth rotates, the angle of the axis with the local horizontal is the local geographical latitude. Unlike the fixed stars, the Sun changes its position on the celestial sphere, being - on north hemisphere - at a positive declination in spring and summer, at a negative declination in autumn and winter, having zero declination at the equinoxes; the Sun's celestial longitude varies, changing by one complete revolution per year. The path of the Sun on the celestial sphere is called the ecliptic; the ecliptic passes through the twelve constellations of the zodiac in the course of a year. This model of the Sun's motion helps to understand sundials. If the shadow-casting gnomon is aligned with the celestial poles, its shadow will revolve at a constant rate, this rotation will not change with the seasons.
This is the most common design. In such cases, the same hour lines may be used throughout the year; the hour-lines will be spaced uniformly if the surface receiving the shadow is either perpendicular or circular about the gnomon