The Göktürk rulers originated from the Ashina clan, who were first attested to 439. The Book of Sui reports that in that year, on October 18, the Tuoba ruler Emperor Taiwu of Northern Wei overthrew Juqu Mujian of the Northern Liang in eastern Gansu,[13][14][15] whence 500 Ashina families fled northwest to the Rouran Khaganate in the vicinity of Gaochang.[7][16] Peter Benjamin Golden points out that the khaghans of the Turkic Khaganate, the Ashina, who were of an undetermined ethnic origin, adopted Iranian and Tokharian titles.[17] German Turkologist W.-E. Scharlipp points out that many common terms in Turkic are Iranian in origin.[18] According to the Book of Zhou and the History of the Northern Dynasties, the Ashina clan was a component of the Xiongnu confederation,[6][8] but this connection is disputed,[19] and according to the Book of Sui and the Tongdian, they were "mixed Hu (barbarians)" (雜胡) from Pingliang.[7][20] Indeed, Chinese sources linked the Hu on their northern borders to the Xiongnu just as Graeco-Roman historiographers called the Pannonian Avars, Huns and Hungarians "Scythians". Such archaizing was a common literary topos, and implied similar geographic origins and nomadic lifestyle but not direct filiation.[21][page needed] As part of the heterogeneous Rouran Khaganate, the Türks lived for generations north of the Altai Mountains, where they 'engaged in metal working for the Rouran'.[7][22] According to Denis Sinor, the rise to power of the Ashina clan represented an 'internal revolution' in the Rouran Khaganate rather than an external conquest.[23] According to Charles Holcombe, the early Tujue population was rather heterogeneous and many of the names of Türk rulers, including the two founding members, are not even Turkic.[24] This is supported by evidence from the Orkhon inscriptions, which include several non-Turkic lexemes, possibly representing Uralic or Yeniseian words.[25][26]