According to Ottoman tradition, he was the son of Suleyman Shah, the leader of the Kayı tribe (a claim which has come under criticism from many historians)[c] of the Oghuz Turks (known as Turkomans by then).

[6][14] According to this legend, after the death of his father, Ertuğrul and his followers entered the service of the Sultanate of Rum, for which he was rewarded with dominion over the town of Söğüt on the frontier with the Byzantine Empire.

Nothing is known with certainty about Ertuğrul's life, other than that he was the father of Osman; historians are thus forced to rely upon stories written about him by the Ottomans more than a century later, which are of questionable accuracy.

[7] Ottoman historian and ambassador to the Qara Qoyunlu, Şükrullah states that Ertuğrul's lineage goes to Gökalp, a son of Oghuz Khagan.

May his kingdom perpetuateIn Enveri's Düsturname (1465) and Karamani Mehmet Pasha's chronicle (before 1481), Gündüz Alp is Ertugrul's father.

[3] After the death of their father, Ertuğrul with his mother Hayme Hatun, Dündar and his followers from the Kayı tribe migrated west into Anatolia and entered the Seljuk Sultanate of Rum, leaving his two brothers who took their clans towards the east.

[7] Osman's mother has been referred to as Halime Hatun in later myths,[citation needed] and there is a grave outside the Ertuğrul Gâzi Tomb which bears the name, but it is disputed.

[38][39] Ertugrul has been portrayed in the Turkish television series Kuruluş/Osmancık [tr] (1988), adapted from a novel by the same name,[40] Diriliş: Ertuğrul (2014–2019)[41] and the sequel Kuruluş: Osman (2019).