East Slavs
By 600 AD, the Slavs had split linguistically into southern, western, and eastern branches. The East Slavs practiced "slash-and-burn" agricultural methods which took advantage of the extensive forests in which they settled. This method of agriculture involved clearing tracts of forest with fire, cultivating it and then moving on after a few years. Slash and burn agriculture requires frequent movement because soil cultivated in this manner only yields good harvests for a few years before exhausting itself, and the reliance on slash and burn agriculture by the East Slavs explains their rapid spread through eastern Europe. The East Slavs flooded Eastern Europe in two streams. One group of tribes settled along the Dnieper river in what is now Ukraine and Belarus to the North; they then spread northward to the northern Volga valley, east of modern-day Moscow and westward to the basins of the northern Dniester and the Southern Buh rivers in present-day Ukraine and southern Ukraine.