Suleyman Shah was, according to Ottoman tradition, the son of Kaya Alp and the father of Ertuğrul, who was the father of Osman I, the founder of the Ottoman Empire. Early Ottoman genealogies disputed this lineage, and either Suleyman Shah or Gündüz Alp could be Osman's grandfather and the father of Ertuğrul. An Ottoman tomb initially in or near Qal'at Ja'bar has historically been associated with Suleyman Shah. He succeeded his father as bey in 1214 when he decided to lead the 50,000 strong tribe West in the face of Mongol invasion. After migrating to the North Caucasus, thousands of Kayis settled in Erzincan and Ahlat in 1214, while some of the other Kayi groups dispersed in Diyarbakir, Mardin, and Urfa.