Ertuğrul or Ertuğrul Gazi was the father of Osman I. Little is known about Ertuğrul's life. According to Ottoman tradition, he was the son of Suleyman Shah, the leader of the Kayı tribe of the Oghuz. 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. An undated coin, supposedly from the time of Osman, with the text "Minted by Osman son of Ertuğrul", suggests that Ertuğrul was a historical figure. Another coin reads "Osman bin Ertuğrul bin Gündüz Alp", though Ertuğrul is traditionally considered the son of Suleyman Shah.
