A Story Of The Great Islamic Warrior Of State Osmania (A Past Story). Ertuğrul was the father of Osman I. According to Ottoman tradition, he was the son of Suleyman Shah, leader of the Kayı tribe of Oghuz Turks, who fled from western Central Asia to Anatolia to escape the Mongol conquests, but he may instead have been the son of a Gündüz Alp.