A caliphate is an Islamic state under the leadership of an Islamic steward with the title of caliph, a person considered a religious successor to the Islamic prophet Muhammad and a leader of the entire ummah. The caliphates were polities based in Islam which developed into multi-ethnic trans-national empires. During the medieval period, three major caliphates succeeded each other: the Rashidun Caliphate, the Umayyad Caliphate and the Abbasid Caliphate. In the fourth major caliphate, the Ottoman Caliphate, the rulers of the Ottoman Empire claimed caliphal authority from 1517. During the history of Islam, a few other Muslim states all hereditary monarchies, have claimed to be caliphates. Prior to the rise of Muhammad and the unification of the tribes of Arabia under Islam, Arabs followed a pre-Islamic Arab polytheism, lived as self-governing sedentary and nomadic communities, raided their neighbouring tribes. Following the early Muslim conquests of the Arabian Peninsula, the region became unified and most of the tribes adopted Islam.
The first caliphate, the Rashidun Caliphate, was established after Muhammad's death in 632. The four Rashidun caliphs, who directly succeeded Muhammad as leaders of the Muslim community, were chosen through shura, a process of community consultation that some consider to be an early form of Islamic democracy; the fourth caliph, who, unlike the prior three, was from the same clan as Muhammad, is considered by Shia Muslims to be the first rightful caliph and Imam after Muhammad. Ali reigned during the First Fitna, a civil war between supporters of Ali and supporters of the assassinated previous caliph, from Banu Umayya, as well as rebels in Egypt; the second caliphate, the Umayyad Caliphate, was ruled by Banu Umayya, a Meccan clan descended from Umayya ibn Abd Shams. The caliphate continued the Arab conquests, incorporating the Caucasus, Sindh, the Maghreb and the Iberian Peninsula into the Muslim world; the caliphate had considerable acceptance of the Christians within its territory, necessitated by their large numbers in the region of Syria.
Following the Abbasid Revolution from 746–750, which arose from non-Arab Muslim disenfranchisement, the Abbasid Caliphate was established in 750. The third caliphate, the Abbasid Caliphate was ruled by the Abbasids, a dynasty of Meccan origin which descended from Hashim, a great-grandfather of Muhammad, making them part of Banu Hashim, via Abbas, an uncle of Muhammad, hence the name. Caliph al-Mansur founded its second capital of Baghdad in 762 which became a major scientific and art centre, as did the territory as a whole during a period known as the Islamic Golden Age. From the 10th century, Abbasid rule became confined to an area around Baghdad. From 945 to 1157, the Abbasid Caliphate came under Buyid and Seljuq military control. In 1250, a non-Arab army created by the Abbasids called. In 1258, the Mongol Empire sacked Baghdad, ending the Abbasid Caliphate, in 1261 the Mamluks in Egypt re-established the Abbasid Caliphate in Cairo. Though lacking in political power, the Abbasid dynasty continued to claim authority in religious matters until the Ottoman conquest of Mamluk Egypt in 1517.
The fourth major caliphate, the Ottoman Caliphate, was established after their conquest of Mamluk Egypt in 1517. The conquest gave the Ottomans control over the holy cities of Mecca and Medina controlled by the Mamluks; the Ottomans came to be viewed as the de facto leaders and representatives of the Muslim world. In the Indian subcontinent, dominant powers such as the Delhi Sultanate's Alauddin Khilji, Mughal Empire's sixth ruler Aurangzeb, Mysore's kings Hyder Ali and Tipu Sultan have been heralded as few of the Indian caliphs existed, due to their establishments of Islamic laws throughout South Asia. Following their defeat in World War I, their empire was partitioned by the United Kingdom and French Third Republic, on 3 March 1924, the first President of the Turkish Republic, Mustafa Kemal Atatürk, as part of his reforms, constitutionally abolished the institution of the caliphate. A few other states that existed through history have called themselves caliphates, including the Isma'ili Fatimid Caliphate in Northeast Africa, the Umayyad Caliphate of Córdoba in Iberia, the Berber Almohad Caliphate in Morocco and the Fula Sokoto Caliphate in present-day northern Nigeria.
The Sunni branch of Islam stipulates that, as a head of state, a caliph may come to power in one of four ways: either through an election, through nomination, through a selection by a committee, or by force. Followers of Shia Islam, believe a caliph should be an Imam chosen by God from the Ahl al-Bayt. In the early 21st century, following the failure of the Arab Spring and defeat of the self-proclaimed "Islamic State", there has seen "a broad mainstream embrace of a collective Muslim identity" by young Muslims and the appeal of a caliphate as a "idealized future Muslim state" has grown stronger. Before the advent of Islam, Arabian monarchs traditionally used the title malik, or another from the same root; the term caliph, derives from the Arabic word khalīfah, which means "successor", "steward", or "deputy" and has traditionally been considered a shortening of Khalīfat Rasūl Allāh. However, studies of pre-Islamic texts suggest that the original meaning of the phr
A map projection is a systematic transformation of the latitudes and longitudes of locations from the surface of a sphere or an ellipsoid into locations on a plane. Maps cannot be created without map projections. All map projections distort the surface in some fashion. Depending on the purpose of the map, some distortions are acceptable and others are not. There is no limit to the number of possible map projections. More the surfaces of planetary bodies can be mapped if they are too irregular to be modeled well with a sphere or ellipsoid. More projections are a subject of several pure mathematical fields, including differential geometry, projective geometry, manifolds. However, "map projection" refers to a cartographic projection. Maps can be more useful than globes in many situations: they are more compact and easier to store; these useful traits of maps motivate the development of map projections. However, Carl Friedrich Gauss's Theorema Egregium proved that a sphere's surface cannot be represented on a plane without distortion.
The same applies to other reference surfaces used as models for the Earth, such as oblate spheroids and geoids. Since any map projection is a representation of one of those surfaces on a plane, all map projections distort; every distinct map projection distorts in a distinct way. The study of map projections is the characterization of these distortions. Projection is not limited to perspective projections, such as those resulting from casting a shadow on a screen, or the rectilinear image produced by a pinhole camera on a flat film plate. Rather, any mathematical function transforming coordinates from the curved surface to the plane is a projection. Few projections in actual use are perspective. For simplicity, most of this article assumes. In reality, the Earth and other large celestial bodies are better modeled as oblate spheroids, whereas small objects such as asteroids have irregular shapes. Io is better modeled by triaxial prolated spheroid with small eccentricities. Haumea's shape is a Jacobi ellipsoid, with its major axis twice as long as its minor and with its middle axis one and half times as long as its minor.
These other surfaces can be mapped as well. Therefore, more a map projection is any method of "flattening" a continuous curved surface onto a plane. Many properties can be measured on the Earth's surface independent of its geography; some of these properties are: Area Shape Direction Bearing Distance ScaleMap projections can be constructed to preserve at least one of these properties, though only in a limited way for most. Each projection compromises, or approximates basic metric properties in different ways; the purpose of the map determines. Because many purposes exist for maps, a diversity of projections have been created to suit those purposes. Another consideration in the configuration of a projection is its compatibility with data sets to be used on the map. Data sets are geographic information. Different datums assign different coordinates to the same location, so in large scale maps, such as those from national mapping systems, it is important to match the datum to the projection; the slight differences in coordinate assignation between different datums is not a concern for world maps or other vast territories, where such differences get shrunk to imperceptibility.
The classical way of showing the distortion inherent in a projection is to use Tissot's indicatrix. For a given point, using the scale factor h along the meridian, the scale factor k along the parallel, the angle θ′ between them, Nicolas Tissot described how to construct an ellipse that characterizes the amount and orientation of the components of distortion. By spacing the ellipses along the meridians and parallels, the network of indicatrices shows how distortion varies across the map; the creation of a map projection involves two steps: Selection of a model for the shape of the Earth or planetary body. Because the Earth's actual shape is irregular, information is lost in this step. Transformation of geographic coordinates to Cartesian or polar plane coordinates. In large-scale maps, Cartesian coordinates have a simple relation to eastings and northings defined as a grid superimposed on the projection. In small-scale maps and northings are not meaningful, grids are not superimposed; some of the simplest map projections are literal projections, as obtained by placing a light source at some definite point relative to the globe and projecting its features onto a specified surface.
This is not the case for most projections, which are defined only in terms of mathematical formulae that have no direct geometric interpretation. However, picturing the light source-globe model can be helpful in understanding the basic concept of a map projection A surface that can be unfolded or unrolled into a plane or sheet without stretching, tearing or shrinking is called a developable surface; the cylinder and the plane are all developable surfaces. The sphere and ellipsoid do not have developable surfaces, so any projection of them onto a plane will have to dis
Judaism is the religion of the Jewish people. It is an ancient, Abrahamic religion with the Torah as its foundational text, it encompasses the religion and culture of the Jewish people. Judaism is considered by religious Jews to be the expression of the covenant that God established with the Children of Israel. Judaism encompasses a wide body of texts, theological positions, forms of organization; the Torah is part of the larger text known as the Tanakh or the Hebrew Bible, supplemental oral tradition represented by texts such as the Midrash and the Talmud. With between 14.5 and 17.4 million adherents worldwide, Judaism is the tenth largest religion in the world. Within Judaism there are a variety of movements, most of which emerged from Rabbinic Judaism, which holds that God revealed his laws and commandments to Moses on Mount Sinai in the form of both the Written and Oral Torah; this assertion was challenged by various groups such as the Sadducees and Hellenistic Judaism during the Second Temple period.
Modern branches of Judaism such as Humanistic Judaism may be nontheistic. Today, the largest Jewish religious movements are Orthodox Judaism, Conservative Judaism, Reform Judaism. Major sources of difference between these groups are their approaches to Jewish law, the authority of the Rabbinic tradition, the significance of the State of Israel. Orthodox Judaism maintains that the Torah and Jewish law are divine in origin and unalterable, that they should be followed. Conservative and Reform Judaism are more liberal, with Conservative Judaism promoting a more traditionalist interpretation of Judaism's requirements than Reform Judaism. A typical Reform position is that Jewish law should be viewed as a set of general guidelines rather than as a set of restrictions and obligations whose observance is required of all Jews. Special courts enforced Jewish law. Authority on theological and legal matters is not vested in any one person or organization, but in the sacred texts and the rabbis and scholars who interpret them.
The history of Judaism spans more than 3,000 years. Judaism has its roots as an organized religion in the Middle East during the Bronze Age. Judaism is considered one of the oldest monotheistic religions; the Hebrews and Israelites were referred to as "Jews" in books of the Tanakh such as the Book of Esther, with the term Jews replacing the title "Children of Israel". Judaism's texts and values influenced Abrahamic religions, including Christianity and the Baha'i Faith. Many aspects of Judaism have directly or indirectly influenced secular Western ethics and civil law. Hebraism was just as important a factor in the ancient era development of Western civilization as Hellenism, Judaism, as the background of Christianity, has shaped Western ideals and morality since Early Christianity. Jews are an ethnoreligious group including those born Jewish, in addition to converts to Judaism. In 2015, the world Jewish population was estimated at about 14.3 million, or 0.2% of the total world population. About 43% of all Jews reside in Israel and another 43% reside in the United States and Canada, with most of the remainder living in Europe, other minority groups spread throughout Latin America, Asia and Australia.
Unlike other ancient Near Eastern gods, the Hebrew God is portrayed as solitary. Judaism thus begins with ethical monotheism: the belief that God is one and is concerned with the actions of mankind. According to the Tanakh, God promised Abraham to make of his offspring a great nation. Many generations he commanded the nation of Israel to love and worship only one God, he commanded the Jewish people to love one another. These commandments are but two of a large corpus of commandments and laws that constitute this covenant, the substance of Judaism. Thus, although there is an esoteric tradition in Judaism, Rabbinic scholar Max Kadushin has characterized normative Judaism as "normal mysticism", because it involves everyday personal experiences of God through ways or modes that are common to all Jews; this is played out through the observance of the Halakha and given verbal expression in the Birkat Ha-Mizvot, the short blessings that are spoken every time a positive commandment is to be fulfilled.
The ordinary, everyday things and occurrences we have, constitute occasions for the experience of God. Such things as one's daily sustenance, the day itself, are felt as manifestations of God's loving-kindness, calling for the Berakhot. Kedushah, nothing else than the imitation of God, is concerned with daily conduct, with being gracious and merciful, with keeping oneself from defilement by idolatry and the shedding of blood; the Birkat Ha-Mitzwot evokes the consciousness of holiness at a rabbinic rite, but the objects employed in the majority of these rites are non-holy and of general character, while the several holy objects are non-theurgic. And not only do ordinary things and occurrences bring with them the experience of God. Everything that happens to a man evokes that exp
Hasan ibn Ali
Al-Ḥasan ibn Alī ibn Abī Ṭālib known as Hasan or Hassan, was the eldest son of Ali and Muhammad's daughter Fatimah, was the older brother of Husayn. Muslims respect him as a grandson of the Islamic Prophet Muhammad. Among Shia Muslims, Hasan is revered as the second Imam. Hasan was elected for the caliphate after his father's death, but abdicated after six or seven months to Muawiyah I, the founder of the Umayyad dynasty to end the First Fitna. Al-Hasan was known for donating to the poor, his kindness to the poor and bondmen, for his knowledge and bravery. For the rest of his life, Hasan lived in Medina, until he died at the age of 45 and was buried in the Jannat al-Baqi cemetery in Medina, his wife, Ja'da bint al-Ash'at, is accused of having poisoned him. When Al-Hasan was born in the year 624 CE, Muhammad slaughtered a ram for the poor on the occasion of his birth, chose the name "Al-Ḥasan" for him. Fatimah shaved his head and gave the weight of his hair in silver as alms. According to Shi'ite belief, theirs was the only house that archangel Gabriel allowed to have a door to the courtyard of al-Masjid an-Nabawi.
Both Shi‘ite and Sunni Muslims consider Al-Hasan to belong to the Bayt of Muhammad, Ahl al-Kisa’, participants of the Event of Mubahalah. There are many narrations showing the respect of Muhammad toward his grandsons, including the statements that his two grandsons would be "sayyedā šabāb of Paradise", that they were Imams "whether they stand up or sit down", he reportedly predicted that Hasan would make peace between two factions of Muslims. In the year AH 10 a Christian envoy from Najran came to Muhammad to argue which of the two parties erred in its doctrine concerning ‘Isa. After likening Jesus' miraculous birth to Adam's creation,—who was born to neither a mother nor a father — and when the Christians did not accept the Islamic doctrine about Jesus, Muhammad was instructed to call them to Mubahalah where each party should ask God to destroy the false party and their families. "If anyone dispute with you in this matter after the knowledge which has come to you, say: Come let us call our sons and your sons, our women and your women and yourselves let us swear an oath and place the curse of God on those who lie."
Except for al-Tabari, who did not name the participants, Sunni historians mention Muhammad, Fatimah, Al-Hasan and Al-Husayn as having participated in the Mubahalah, some agree with the Shi'ite tradition that ‘Ali was among them. Accordingly, in the Shi'ite perspective, in the verse of Mubahalah, the phrase "our sons" would refer to Al-Hasan and Al-Husayn, "our women" refers to Fatimah, "ourselves" refers to ‘Ali, it is said that one day, the ‘Abbasid Caliph Harun al-Rashid questioned the seventh Twelver Shi‘ite Imam, Musa al-Kadhim, saying why he had permitted people to call him "Son of the Apostle of Allah", while he and his forefathers were Muhammad's daughter's children, that "the progeny belongs to the male and not to the female". In response al-Kadhim recited the verses Quran, 6:84 and Quran, 6:85 and asked "Who is Jesus' father, O Commander of the faithful?". "Jesus had no father", said Harun. Al-Kadhim argued that God, in these verses, had ascribed Jesus to descendants of Prophets, through Mary, saying "similarly, we have been ascribed to the descendants of the Prophet through our mother Fatimah".
It is related that Harun asked Musa to give him more evidence and proof. Al-Kadhim thus recited the verse of Mubahalah, argued "None claims that the Prophet made someone enter under the cloak when he challenged the Christians to a contest of prayer to God, except ‘Ali, Fatimah, Al-Hasan, Al-Husayn. So in the verse,'Our sons' refers to Al-Hasan and Al-Husayn." Al-Hasan was one of the guards defending ‘Uthman ibn ‘Affan when the attackers went round the latter and killed him. During the reign of ‘Ali, he was a participant in the Battles of Siffin and Jamal. According to Donaldson there was not a significant difference between the idea of Imamate, or divine right, expressed by each Imam designating his successor and other ideas of succession at first. ‘Ali had failed to nominate a successor before he died, however, on several occasions expressed his idea that "only the Prophet's Bayt were entitled to rule the Community", Hasan, whom he had appointed his inheritor, must have been the obvious choice, as he would be chosen by people to be the next caliph.
Sunnis, on the other hand, reject Imamate on the basis of their interpretation of verse 33:40 of the Qur'an which says that Muhammad, as the Khatam an-Nabiyyin, "is not the father of any of your men". This is why Muhammad did not nominate a successor, as he wanted to leave the succession to be resolved "by the Muslim Community on the basis of the Qur’anic principle of consultation"; the question Madelung proposes here is why the family members of Muhammad should not inherit other aspects of Muhammad's character such as Hukm and Imamah. Since the Sunni concept of the "true caliphate" itself defines it as a "succession of the Prophet in every respect except his prophethood", Madelung further asks "If God wanted to indicate that he should not be succeeded by any of his family, why did He not let his grandsons and other kin die like his sons?" A
Arabic is a Central Semitic language that first emerged in Iron Age northwestern Arabia and is now the lingua franca of the Arab world. It is named after the Arabs, a term used to describe peoples living in the area bounded by Mesopotamia in the east and the Anti-Lebanon mountains in the west, in northwestern Arabia, in the Sinai Peninsula. Arabic is classified as a macrolanguage comprising 30 modern varieties, including its standard form, Modern Standard Arabic, derived from Classical Arabic; as the modern written language, Modern Standard Arabic is taught in schools and universities, is used to varying degrees in workplaces and the media. The two formal varieties are grouped together as Literary Arabic, the official language of 26 states, the liturgical language of the religion of Islam, since the Quran and Hadith were written in Arabic. Modern Standard Arabic follows the grammatical standards of Classical Arabic, uses much of the same vocabulary. However, it has discarded some grammatical constructions and vocabulary that no longer have any counterpart in the spoken varieties, has adopted certain new constructions and vocabulary from the spoken varieties.
Much of the new vocabulary is used to denote concepts that have arisen in the post-classical era in modern times. Due to its grounding in Classical Arabic, Modern Standard Arabic is removed over a millennium from everyday speech, construed as a multitude of dialects of this language; these dialects and Modern Standard Arabic are described by some scholars as not mutually comprehensible. The former are acquired in families, while the latter is taught in formal education settings. However, there have been studies reporting some degree of comprehension of stories told in the standard variety among preschool-aged children; the relation between Modern Standard Arabic and these dialects is sometimes compared to that of Latin and vernaculars in medieval and early modern Europe. This view though does not take into account the widespread use of Modern Standard Arabic as a medium of audiovisual communication in today's mass media—a function Latin has never performed. During the Middle Ages, Literary Arabic was a major vehicle of culture in Europe in science and philosophy.
As a result, many European languages have borrowed many words from it. Arabic influence in vocabulary, is seen in European languages Spanish and to a lesser extent Portuguese, Catalan, owing to both the proximity of Christian European and Muslim Arab civilizations and 800 years of Arabic culture and language in the Iberian Peninsula, referred to in Arabic as al-Andalus. Sicilian has about 500 Arabic words as result of Sicily being progressively conquered by Arabs from North Africa, from the mid-9th to mid-10th centuries. Many of these words relate to related activities; the Balkan languages, including Greek and Bulgarian, have acquired a significant number of Arabic words through contact with Ottoman Turkish. Arabic has influenced many languages around the globe throughout its history; some of the most influenced languages are Persian, Spanish, Kashmiri, Bosnian, Bengali, Malay, Indonesian, Punjabi, Assamese, Sindhi and Hausa, some languages in parts of Africa. Conversely, Arabic has borrowed words from other languages, including Greek and Persian in medieval times, contemporary European languages such as English and French in modern times.
Classical Arabic is the liturgical language of 1.8 billion Muslims, Modern Standard Arabic is one of six official languages of the United Nations. All varieties of Arabic combined are spoken by as many as 422 million speakers in the Arab world, making it the fifth most spoken language in the world. Arabic is written with the Arabic alphabet, an abjad script and is written from right to left, although the spoken varieties are sometimes written in ASCII Latin from left to right with no standardized orthography. Arabic is a Central Semitic language related to the Northwest Semitic languages, the Ancient South Arabian languages, various other Semitic languages of Arabia such as Dadanitic; the Semitic languages changed a great deal between Proto-Semitic and the establishment of the Central Semitic languages in grammar. Innovations of the Central Semitic languages—all maintained in Arabic—include: The conversion of the suffix-conjugated stative formation into a past tense; the conversion of the prefix-conjugated preterite-tense formation into a present tense.
The elimination of other prefix-conjugated mood/aspect forms in favor of new moods formed by endings attached to the prefix-conjugation forms. The development of an internal passive. There are several features which Classical Arabic, the modern Arabic varieties, as well as the Safaitic and Hismaic inscriptions share which are unattested in any other Central Semitic language variety, including the Dadanitic and Taymanitic languages of the northern Hejaz; these features are evidence of common descent from Proto-Arabic. The following features can be reconstructed with confidence for Proto-Arabic: negative particles m *mā.
An astrolabe is an elaborate inclinometer used by astronomers and navigators to measure the altitude above the horizon of a celestial body, day or night. It can be used to identify stars or planets, to determine local latitude given local time, to survey, or to triangulate, it was used in classical antiquity, the Islamic Golden Age, the European Middle Ages and the Age of Discovery for all these purposes. The astrolabe's importance not only comes from the early development of astronomy, but is effective for determining latitude on land or calm seas. Although it is less reliable on the heaving deck of a ship in rough seas, the mariner's astrolabe was developed to solve that problem. OED gives the translation "star-taker" for the English word astrolabe and traces it through medieval Latin to the Greek word astrolabos, from astron "star" and lambanein "to take". In the medieval Islamic world the Arabic word "al-Asturlāb" was given various etymologies. In Arabic texts, the word is translated as "ākhdhu al-Nujuum", a direct translation of the Greek word.
Al-Biruni quotes and criticizes medieval scientist Hamzah al-Isfahani who stated: "asturlab is an arabization of this Persian phrase". In medieval Islamic sources, there is a folk etymology of the word as "lines of lab", where "Lab" refers to a certain son of Idris; this etymology is mentioned by a 10th-century scientist rejected by al-Khwarizmi. An early astrolabe was invented in the Hellenistic civilization by Apollonius of Perga between 220 and 150 BC attributed to Hipparchus; the astrolabe was a marriage of the planisphere and dioptra an analog calculator capable of working out several different kinds of problems in astronomy. Theon of Alexandria wrote a detailed treatise on the astrolabe, Lewis argues that Ptolemy used an astrolabe to make the astronomical observations recorded in the Tetrabiblos; the invention of the plane astrolabe is sometimes wrongly attributed to Theon's daughter Hypatia, but it is, in fact, known to have been in use at least 500 years before Hypatia was born. The misattribution comes from a misinterpretation of a statement in a letter written by Hypatia's pupil Synesius, which mentions that Hypatia had taught him how to construct a plane astrolabe, but does not state anything about her having invented it herself.
Astrolabes continued in use in the Greek-speaking world throughout the Byzantine period. About 550 AD, Christian philosopher John Philoponus wrote a treatise on the astrolabe in Greek, the earliest extant treatise on the instrument. Mesopotamian bishop Severus Sebokht wrote a treatise on the astrolabe in the Syriac language in the mid-7th century. Sebokht refers to the astrolabe as being made of brass in the introduction of his treatise, indicating that metal astrolabes were known in the Christian East well before they were developed in the Islamic world or in the Latin West. Astrolabes were further developed in the medieval Islamic world, where Muslim astronomers introduced angular scales to the design, adding circles indicating azimuths on the horizon, it was used throughout the Muslim world, chiefly as an aid to navigation and as a way of finding the Qibla, the direction of Mecca. Eighth-century mathematician Muhammad al-Fazari is the first person credited with building the astrolabe in the Islamic world.
The mathematical background was established by Muslim astronomer Albatenius in his treatise Kitab az-Zij, translated into Latin by Plato Tiburtinus. The earliest surviving astrolabe is dated AH 315. In the Islamic world, astrolabes were used to find the times of sunrise and the rising of fixed stars, to help schedule morning prayers. In the 10th century, al-Sufi first described over 1,000 different uses of an astrolabe, in areas as diverse as astronomy, navigation, timekeeping, Salat, etc; the spherical astrolabe was a variation of both the astrolabe and the armillary sphere, invented during the Middle Ages by astronomers and inventors in the Islamic world. The earliest description of the spherical astrolabe dates back to Al-Nayrizi. In the 12th century, Sharaf al-Dīn al-Tūsī invented the linear astrolabe, sometimes called the "staff of al-Tusi", "a simple wooden rod with graduated markings but without sights, it was furnished with a plumb line and a double chord for making angular measurements and bore a perforated pointer".
The geared mechanical astrolabe was invented by Abi Bakr of Isfahan in 1235. Herman Contractus, the abbot of Reichman Abbey, examined the use of the astrolabe in Mensura Astrolai during the 11th century. Peter of Maricourt wrote a treatise on the construction and use of a universal astrolabe in the last half of the 13th century entitled Nova compositio astrolabii particularis. Universal astrolabes can be found at the History of Science Museum in Oxford. English author Geoffrey Chaucer compiled A Treatise on the Astrolabe for his son based on a work by Messahalla or Ibn al-Saffar; the same source was translated by others. The first printed book on the astrolabe was Composition and Use of Astrolabe by Christian of Prachatice using Messahalla, but original. In 1370, the first Indian treatise on the astrolabe was written by the Jain astronomer Mahendra Suri. A simplified astrolabe, known as a balesilha, was used by sailors to get an accurate reading of latitude while out to sea; the use of
The Ilkhanate spelled Il-khanate, was established as a khanate that formed the southwestern sector of the Mongol Empire, ruled by the Mongol House of Hulagu. It was founded in the 13th century and was based in Iran as well as neighboring territories, such as present-day Azerbaijan and the central and eastern parts of present-day Turkey; the Ilkhanate was based on the campaigns of Genghis Khan in the Khwarazmian Empire in 1219–24 and was founded by Hulagu Khan, son of Tolui and grandson of Genghis Khan. With the fragmentation of the Mongol Empire after 1259 it became a functionally separate khanate. At its greatest extent, the state expanded into territories that today comprise most of Iran, Armenia, Georgia, Turkey, western Afghanistan, the Northwestern edge of the Indian sub-continent. Ilkhanate rulers, beginning with Ghazan in 1295, converted to Islam. According to the historian Rashid-al-Din Hamadani, Kublai Khan granted Hulagu the title of Ilkhan after his defeat of Ariq Böke; the term ilkhan here means " khan of the tribe, khan of the'ulus'" and this inferior "khanship" refers to the initial deference to Möngke Khan and his successor Great Khans of the Mongol empire.
The title "Ilkhan", borne by the descendants of Hulagu and other Borjigin princes in Persia, does not materialize in the sources until after 1260. When Muhammad II of Khwarezm executed a contingent of merchants dispatched by the Mongols, Genghis Khan declared war on the Khwārazm-Shāh dynasty in 1219; the Mongols overran the empire, occupying the major cities and population centers between 1219 and 1221. Persian Iran was ravaged by the Mongol detachment under Subedei, who left the area in ruin. Transoxiana came under Mongol control after the invasion; the undivided area west of the Transoxiana was the inheritance of Genghis Khan's Borjigin family. Thus, the families of the latter's four sons appointed their officials under the Great Khan's governors, Chin-Temür, Korguz, in that region. Muhammad's son Jalal ad-Din Mingburnu returned to Iran in c. 1224 after his exile in India. The rival Turkic states, which were all that remained of his father's empire declared their allegiance to Jalal, he repulsed the first Mongol attempt to take Central Persia.
However, Jalal ad-Din was overwhelmed and crushed by Chormaqan's army sent by the Great Khan Ögedei in 1231. During the Mongol expedition and the southern Persian dynasties in Fars and Kerman voluntarily submitted to the Mongols and agreed to pay tribute. To the west and the rest of Persia was secured by Chormaqan; the Mongols invaded Armenia and Georgia in 1234 or 1236, completing the conquest of the Kingdom of Georgia in 1238. They began to attack the western parts of Greater Armenia, under the Seljuks, the following year. In 1236 Ögedei proceeded to populate Herat; the Mongol military governors made camp in the Mughan plain in what is now Azerbaijan. Realizing the danger posed by the Mongols, the rulers of Mosul and Cilician Armenia submitted to the Great Khan. Chormaqan divided the Transcaucasia region into three districts based on the Mongol military hierarchy. In Georgia, the population was temporarily divided into eight tumens. By 1237 the Mongol Empire had subjugated most of Persia, Georgia, as well as all of Afghanistan and Kashmir.
After the battle of Köse Dağ in 1243, the Mongols under Baiju occupied Anatolia, while the Seljuk Sultanate of Rûm and the Empire of Trebizond became vassals of the Mongols. Güyük Khan abolished decrees issued by the Mongol princes that had ordered the raising of revenue from districts in Persia as well as offering tax exemptions to others in c. 1244. In accordance with a complaint by the governor Arghun the Elder, Möngke Khan prohibited ortog-merchants and nobles from abusing relay stations and civilians in 1251, he ordered a new census and decreed that each man in the Mongol-ruled Middle East must pay in proportion to his property. Persia was divided between four districts under Arghun. Möngke Khan granted the Kartids authority over Herat, Pushang, Khaysar, Firuz-Kuh, Farah, Kabul and Afghanistan; the founder of the Ilkhanate dynasty was Hulagu Khan, grandson of Genghis Khan and brother of both Möngke Khan and Kublai Khan. Möngke dispatched Hulagu to establish a firm Toluid control over the Middle East and ordered him return to Mongolia when his task was accomplished.
Taking over from Baiju in 1255 or 1256, Hulagu had been charged with subduing the Muslim kingdoms to the west "as far as the borders of Egypt". This occupation led the Turkmens to move west into Anatolia to escape from the Mongolian rule, he established his dynasty over the southwestern part of the Mongol Empire that stretched from Transoxiana to Syria. He destroyed the Ismaili Nizari Hashshashins and the Abbasid Caliphate in 1256 and 1258 respectively. After that he advanced as far as Gaza conquering Ayyubid Syria; the death of Möngke forced Hulagu to return from the Persian heartland for the preparation of Khurultai. He left a small force behind to continue the Mongol advance, but it was halted in Palestine in 1260 by a major defeat at the battle of Ain Jalut at the hands of the Mamluks of Egypt. Due to geo-political and religious issues and deaths of three Jochid princes in Hulagu's service, Berke declared open war on Hulagu in 1262 and called his troops back to Iran. According to Mamluk historians, Hulagu might have massacred Berke's troops and refused to share his war booty with Berke.
Hulagu's descendants r