The Khazars were a semi-nomadic Turkic people with a confederation of Turkic-speaking tribes that in the late 6th century CE established a major commercial empire covering the southeastern section of modern European Russia. The Khazars created what for its duration was the most powerful polity to emerge from the break-up of the Western Turkic Khaganate. Astride a major artery of commerce between Eastern Europe and Southwestern Asia, Khazaria became one of the foremost trading empires of the medieval world, commanding the western marches of the Silk Road and playing a key commercial role as a crossroad between China, the Middle East and Kievan Rus'. For some three centuries the Khazars dominated the vast area extending from the Volga-Don steppes to the eastern Crimea and the northern Caucasus. Khazaria long served as a buffer state between the Byzantine Empire and both the nomads of the northern steppes and the Umayyad Caliphate, after serving as Byzantium's proxy against the Sasanian Persian empire.

The alliance was dropped around 900. Byzantium began to encourage the Alans to attack Khazaria and weaken its hold on Crimea and the Caucasus, while seeking to obtain an entente with the rising Rus' power to the north, which it aspired to convert to Christianity. Between 965 and 969, the Kievan Rus' ruler Sviatoslav I of Kiev conquered the capital Atil and destroyed the Khazar state. Determining the origins and nature of the Khazars is bound with theories of their languages, but it is a matter of intricate difficulty since no indigenous records in the Khazar language survive, the state was polyglot and polyethnic; the native religion of the Khazars is thought to have been Tengrism, like that of the North Caucasian Huns and other Turkic peoples. The polyethnic populace of the Khazar Khaganate appears to have been a multiconfessional mosaic of pagan, Jewish and Muslim worshippers; the ruling elite of the Khazars was said by Judah Halevi and Abraham ibn Daud to have converted to Rabbinic Judaism in the 8th century, but the scope of the conversion within the Khazar Khanate remains uncertain..

Proposals of Khazar origins have been made regarding the Bukharan Jews, the Muslim Kumyks, the Cossacks of the Don region, the Turkic-speaking Krymchaks and their Crimean neighbours the Karaites, to the Moldavian Csángós, the Mountain Jews and others. In the late 19th century, a theory emerged that the core of today's Ashkenazi Jews descended from a hypothetical Khazarian Jewish diaspora who had migrated westward from modern Russia and Ukraine into modern France and Germany. Linguistic and genetic studies have not supported a connection to Ashkenazi Jewry; the theory still finds occasional support. The theory is sometimes associated with anti-Zionism. Gyula Németh, following Zoltán Gombocz, derived Xazar from a hypothetical *Qasar reflecting a Turkic root qaz- being an hypothetical velar variant of Common Turkic kez-. In the fragmentary Tes and Terkhin inscriptions of the Uyğur empire the form'Qasar' is attested, though uncertainty remains whether this represents a personal or tribal name other hypotheses emerged.

Louis Bazin derived it from Turkic qas- on the basis of its phonetic similarity to the Uyğur tribal name, Qasar. András Róna-Tas connects it with the Pahlavi transcription of the Roman title Caesar. D. M. Dunlop tried to link the Chinese term for "Khazars" to one of the tribal names of the Uyğur Toquz Oğuz, namely the Gésà; the objections are that Uyğur Gesa/Qasar was not a tribal name but rather the surname of the chief of the 思结 Sijie tribe of the Toquz Oğuz, that in Middle Chinese the ethnonym "Khazars", always prefaced with the word Tūjué, is transcribed with characters different from those used to render the Qa- in the Uyğur word'Qasar'. After their conversion it is reported that they adopted the Hebrew script, it is that, though speaking a Türkic language, the Khazar chancellery under Judaism corresponded in Hebrew. In Expositio in Matthaeum Evangelistam, Gazari Khazars, are referred to as the Hunnic people living in the lands of Gog and Magog and said to be circumcised and omnem Judaismum observat, observing all the laws of Judaism.

While the Khazar language went extinct centuries ago, modern Turkic languages still refer to the Caspian Sea as the "Khazar Sea". Determining the origins and nature of the Khazars is bound with theories of their languages, but it is a matter of intricate difficulty, since no indigenous records in the Khazar language survive, the state was polyglot and polyethnic. Whereas the royal or ruling elite spoke an eastern variety of Shaz Turkic, the subject tribes appear to have spoken varieties of Lir Turkic, such as Oğuric, a language variously identified with Bulğaric and Hunnish. One method for tracing their origins consists in analysis of the possible etymologies behind the ethnonym "Khazar"; the tribes that were to comprise the Khazar empire were not an ethnic union, but a congeries of steppe nomads and peoples who came to be subordinated, subscribed to a core Turkic leadership. Many Turkic groups, such as the Oğuric peoples, including Šarağurs, Oğurs, Onoğurs, Bulğars who

Shinsarugakuki is an 11th-century Japanese work of fiction written by Fujiwara no Akihira. The work consists of an introduction and twenty-eight short chapters and portrays a sarugaku performance took place in Kyoto and the family of a military official Uemon-no-jō in the audience. While describing the performance in the introduction and the members of Uemon-no-jō's family, namely his three wives, sixteen daughters and/or their husbands, nine sons, in the following chapters, the narrative incorporates various words related to performing arts and the respective occupation of the figures and thus provides the readers with lists of objects. For example, the book provides in the introduction an account of various performances, including comic sketches, lion dances, rice-planting songs, solo sumo wrestling; as a result, Shinsarugakuki is considered to be one of the most important sources relating the lives and society of the time. The husband of Uemon-no-jō's third daughter Tanaka no Toyomasu is a farmer and therefore the narrator describes the life of an idealistic landholding farmer in the chapter.

Toyomasu is described as a farmer with land holdings. He meticulously tills his lands at the right time, with his own agricultural implements of Chinese origin, he has skills to mend them as required and has an excellent reputation with people who work with him on his fields. He pays for additional work to restore the embankment paths along the rice fields, he ensures the sowing season for late crops of rice, as well as glutinous rice. The farmer is present during the planting of all other crops, such as barley, soy bean, millet and sesame in the regular season, assuring that they are all observed, that the workers, both men and women, who help him in this planning process, are duly rewarded, he does not believe in the wasting of sowing grains. His return at the end of harvest and pounding is always several fold more; the eighth son Hachirō-mauto is a trader and in his description, the author gives an account of both domestic and international trades, revealing an insight into trade in East Asia at the time.

Hachirō-mauto is supposed to have traveled to the land of the Emishi in the east and to Kikai Island in the west. The items listed as the goods he imports include perfumes, animal hides, dyes and nuts from Korea, South Asia, South East Asia, Central Asia. In more detail, they are "spices and fragrances such as Aloeswood, cloves, sandalwood oil, birtwarth root, camphor. Except for minerals, the other goods originated from forests of South and Southeast Asia transported by ship to East Asia. For the pan-European network of exchange, Japan was the terminus

Walter Alvarez is a professor in the Earth and Planetary Science department at the University of California, Berkeley. He is most known for the theory that dinosaurs were killed by an asteroid impact, developed in collaboration with his father, Nobel Prize winning physicist Luis Alvarez. Born in Berkeley, Alvarez is the son of Luis Walter Alvarez, a Nobel prize-winner in physics, his grandfather was the famed physics researcher Walter C. Alvarez and his great-grandfather, Spanish-born Luis F. Alvarez, worked as a doctor in Hawaii and developed a method for the better diagnosis of macular leprosy, his great-aunt Mabel Alvarez was a noted California oil painter. Alvarez earned his B. A. in geology in 1962 from Carleton College in Minnesota and Ph. D. in geology from Princeton University in 1967. He worked for American Overseas Petroleum Limited in the Netherlands, in Libya at the time of Colonel Gadaffi's revolution. Having developed a side interest in archaeological geology, he left the oil company and spent some time in Italy, studying the Roman volcanics and their influence on patterns of settlement in early Roman times.

Alvarez moved to Lamont-Doherty Geological Observatory of Columbia University, began studying the Mediterranean tectonics in the light of the new theory of plate tectonics. His work on tectonic paleomagnetism in Italy led to a study of the geomagnetic reversals recorded in Italian deep-sea limestones. Alvarez and his colleagues were able to date the reversals for an interval of more than 100 million years of the Earth's history by using Foraminifera biostratigraphy. Alvarez and his father Luis W. Alvarez are most known for their discovery that a clay layer occurring right at the Cretaceous–Paleogene boundary was enriched in the element iridium. Since iridium enrichment is common in asteroids, but uncommon on the Earth, they further postulated that the layer had been created by the impact of a large asteroid with the Earth and that this impact event was the cause of the Cretaceous–Paleogene extinction event; this iridium enrichment has now been observed in many other sites around the world. And further, the large Chicxulub crater was identified and is now regarded as the definitive evidence of a large impact.

A majority of scientists now accept the impact scenario as the most cause for the Cretaceous–Paleogene extinction event which occurred 66 million years ago and eliminated 75% of all species, including all non-avian dinosaurs. His book, T. Rex and the Crater of Doom, details the discovery of the Cretaceous–Paleogene extinction event. In addition to his interest in extinction events and impacts, Alvarez has contributed to the understanding of Mediterranean tectonics, Roman geology and archeology, the establishment of magnetostratigraphic correlations. Alvarez began teaching a course in Big History at UC Berkeley in 2006 under the title "Big History: Cosmos, Life, Humanity." He last taught the course in 2011 where it was videotaped and made available online. According to Alvarez, Big History is the "attempt to understand, in a unified and interdisciplinary way, the history of the Cosmos, Earth and Humanity." This definition was adopted by the International Big History Association. Alvarez's course is open to all majors and grade levels and seeks to provide a broad understanding of the past and future.

Alvarez helped organize a meeting of Big Historians at the Geological Observatory at Coldigioco in Italy in 2010 which resulted in the establishment of the International Big History Association. In 2011, the IBHA is a 5013 non-profit organization. Alvarez was one of the founding members of the IBHA, served on the advisory board until August 7, 2014 when he stepped down at the 2014 IBHA conference held at Dominican University of California. Alvarez's most recent contribution to the field of Big History has been the creation of a free, open source, zoomable timeline in partnership with Microsoft Research called ChronoZoom. ChronoZoom is a computer-graphical approach to dealing with this problem of visualizing and understanding time scales, presenting vast quantities of historical information in a useful way. ChronoZoom was introduced at the 97th Annual Faculty Research Lecture at UC Berkeley. Alvarez is the recipient of numerous honors, he was elected a Fellow of the American Academy of Arts and Sciences in 1983, elected a member of the National Academy of Sciences in 1991.

He was awarded the 2006 Nevada Medal, the 2008 Vetlesen Prize, the Penrose Medal from the Geological Society of America. In 2005, he received the doctorate "Honoris Causa" in Geological Sciences from the University of Siena, Italy. T. Rex and the Crater of Doom ISBN 0-375-70210-5 The Mountains of Saint Francis: The Geologic Events that Shaped Our Earth ISBN 9780393061857 A Most Improbable Journey: A Big History of our Planet and Ourselves ISBN 978-0393292695 Walter Alvarez's Berkeley homepage ChronoZoom project homepage 97th Annual Faculty Research Lectures: Walter Alvarez on YouTube