The pattern of lifeways established by the first millennium B.C. continues in North and Central Asia. Far to the north, tribes continue to live a hunting and gathering existence. On the northern steppes, with settled sites interspersed, nomadic groups herd their animals and form military alliances. These alliances often harass or conquer the settled populations to the south, east, and west, and it is only at those times that the historical sources tell us much about them. The Sarmatians, Hephthalites, Chionites, Huns, and Turkish tribes come from the steppes. In the oasis areas further south, independent kingdoms rule in some, and others are incorporated into the large empires at the eastern and western ends of the area. Some independent kingdoms, like Sogdiana, play a significant role in the trade between East and West.