The grandson of a princess of the Grand Komnenoi, Uzun Hasan had made the Aq Qoyunlu into the most powerful tribe of Turkmen by defeating their rivals the Black Sheep; he had heard of the beauty of the Emperor John's daughter Theodora Komnene (or Despina Khatun), and in return for her hand, Uzun Hasan pledged himself to protect her home city with his men, his money, and his person.[14]