Although Turko-Mongol infiltration into Central Asia had started early,and the influence of the Turkic tribes was felt in Khwarazm before the campaigns of the Mongols, after the beginning of the Chingizid rule, bilingualism became more common. It is generally believed that these ancient Indo-European-speaking peoples were linguistically assimilated by smaller but dominant Turkic-speaking groups while the sedentary population finally adopted the Persian language, the traditional "lingua franca" of the eastern Islamic lands. The language-shift from Middle Iranian to Turkic and New Persian was predominantly the result of an "elite dominance" process. This process was dramatically boosted during the Mongol conquest when millions were either killed or pushed further south to the Pamir region. Peter B. Golden listed three basic ethnic elements contributing to the Uzbeks' ethnogenesis: