The East Slavs are Slavic peoples speaking East Slavic languages. Formerly the main population of the medieval state of Kievan Rus, by the seventeenth century they evolved into the Russian, Ukrainian and Belarusian people.
Researchers know relatively little about the Eastern Slavs prior to approximately 859 AD, when the first events recorded in the Primary Chronicle occurred. The Eastern Slavs of these early times apparently lacked a written language. The few known facts come from archaeological digs, foreign travellers' accounts of the Rus' land, and linguistic comparative analyses of Slavic languages.
Very few native Rus' documents dating before the 11th century (none before the 10th century) have survived. The earliest major manuscript with information on Rus' history, the Primary Chronicle, dates from the late 11th and early 12th centuries. It lists twelve Slavic tribal unions which, by the 10th century, had settled in the later territory of the Kievan Rus between the Western Bug, the Dniepr and the Black Sea: the Polans, Drevlyans, Dregovichs, Radimichs, Vyatichs, Krivichs, Slovens, Dulebes (later known as Volhynians and Buzhans), White Croats, Severians, Ulichs, and Tivertsi.
Slavs are the largest Indo-European ethno-linguistic group in Europe. They inhabit Central Europe, Eastern Europe, Southeast Europe, North Asia and Central Asia. Slavs speak Indo-European Slavic languages and share, to varying degrees, some cultural traits and historical backgrounds. From the early 6th century they spread to inhabit most of Central and Eastern Europe and Southeast Europe, whilst Slavic mercenaries fighting for the Byzantines and Arabs settled Asia Minor and even as far as Syria. The East Slavs colonised Siberia and Central Asia. Presently over half of Europe's territory is inhabited by Slavic-speaking communities, but every Slavic ethnicity has emigrated to other continents.
Present-day Slavic people are classified into West Slavic (chiefly Poles, Czechs and Slovaks), East Slavic (chiefly Russians, Belarusians, and Ukrainians), and South Slavic (chiefly Serbs, Bulgarians, Croats, Bosniaks, Macedonians, Slovenes, and Montenegrins), though sometimes the West Slavs and East Slavs are combined into a single group known as North Slavs. For a more comprehensive list, see the ethnocultural subdivisions. Modern Slavic nations and ethnic groups are considerably diverse both genetically and culturally, and relations between them – even within the individual ethnic groups themselves – are varied, ranging from a sense of connection to mutual feelings of hostility.