The name of their eponymous ruler "Kidara" (fl. 350–385) may be cognate with the Turkic word "Kidirti" meaning "west", suggesting that the Kidarites were originally the westernmost of the Xionites, and the first to migrate from Inner Asia. Chinese sources suggest that when the Uar (滑 "Huá") were driven westward by the Later Zhao state, circa 320, from the area around Pingyang (平陽; modern Linfen, Shanxi), it put pressure on Xionite-affiliated peoples, such as the Kidarites, to migrate. Another theory is that climate change in the Altai during the 4th century caused various tribes to migrate westward and southward.