Founded in 1270 by the Solomonic Dynasty nobleman Yekuno Amlak, who claimed to descend from the last Aksumite king and ultimately the Biblical Menelik I and the Queen of Sheba, it replaced the Agaw kingdom of the Zagwe. While initially a rather small and politically unstable entity, the Empire managed to expand significantly under the crusades of Amda Seyon I (1314–1344) and Yeshaq I (1414–1429), temporarily becoming the dominant force of the African Horn. Yeshaq's reign was however challenged by Sultan Jamal ad-Din II which led to Yeshaq's death. Under the rule of Zara Yaqob (1434–1468), the Hadiya Sultanate was invaded by Ethiopia and the captured Hadiya princess Eleni converted to Christianity leading to her marriage to Zara Yacob. Muslims in the region as well as Adal Sultanate rejected the marriage alliance and began launching several invasion attempts into Ethiopia finally succeeding under Imam Mahfuz. Mahfuz's ambush and defeat by Emperor Lebna Dengel brought about the early 16th century Jihad of the Adalite Imam Ahmed Gran, who was only defeated in 1543 with the help of the Portuguese. Greatly weakened, much of the Empire's southern territory and vassals were lost due to the Oromo migrations. In the north, in what is now Eritrea, Ethiopia managed to repulse Ottoman invasion attempts, although losing its access to the Red Sea to them.