Between the age of the Xiongnu Empire and the rise of the Gokturks, the Rouran Khaganate ruled what was the vast steppe lands of Central Asia. The Rourans inherited the stratified political system of their Xianbei ancestors and had rulers with broad sweeping political powers. As such they were perhaps the first people to use the title of "Khan" or "Khagan". For two centuries, they would rule as a powerful force in Central Asia, uniting a colossal host of powerful tribes under their banner. During these centuries they were a constant threat to China's Northern Wei dynasty. However, the Rouran's reign would be suddenly overthrown by the insurgency of one of their vassal tribes- the Göktürks.
The remnants of the Rouran may have fled west after that and became the Pannonian Avars, however this is a contested theory among historians. The Göktürks chased after these "Avars" into the Byzantine Empire and referred to them as "Varconites" who were escaped slaves of the Türks.