At least some Turkic tribes were involved in the formation of the Xionites, despite their later character as an Eastern Iranian people, according to Richard Nelson Frye (1991): "Just as later nomadic empires were confederations of many peoples, we may tentatively propose that the ruling groups of these invaders were, or at least included, Turkic-speaking tribesmen from the east and north, although most probably the bulk of the people in the confederation of Chionites... spoke an Iranian language... This was the last time in the history of Central Asia that Iranian-speaking nomads played any role; hereafter all nomads would speak Turkic languages".