Markos was born near Beijing (Khanbaliq, or Taitu), but his ethnic ancestry is not entirely clear. According to the Ecclesiastical Chronicle of Bar-Hebraeus he was of Turkish Uyghur descent. He was also referred to as 'Yaballaha the Turk' in the colophon to an East Syrian manuscript of 1301. On the other hand, the History of Mar Yaballaha III names the place of his birth as Koshang, thus perhaps suggesting that he was an Ongud from the Christian tribe's homeland in Inner Mongolia near Shanxi.