The Aq Qoyunlu or the White Sheep Turkomans was a Turkoman, culturally Persianate, Sunni Muslim tribal confederation. Founded in the Diyarbakir region by Qara Yuluk Uthman Beg, they ruled parts of present-day eastern Turkey from 1378 to 1508, and in their last decades also ruled Armenia, Azerbaijan, much of Iran, Iraq, and Oman where the ruler of Hormuz recognised Aq Qoyunlu suzerainty. The Aq Qoyunlu empire reached its zenith under Uzun Hasan. 
 
Uzun Hasan used to assert the claim that he was an "honorable descendant of Oghuz Khan and his grandson, Bayandur Khan". In a letter dating to the year 1470, which was sent to Şehzade Bayezid, the then-governor of Amasya, Uzun Hasan wrote that those from the Bayandur and Bayat tribes, as well as other tribes that belonged to the "Oghuz il", and formerly inhabited Mangyshlak, Khwarazm and Turkestan, came and served in his court. He also made the tamga (seal) of the Bayandur tribe the symbol of his state. For this reason, the Bayandur tamga is found in Aq Qoyunlu coins, their official documents, inscriptions and flags.[13]