Musa Çelebi became Sultan of the Ottoman Empire following the tumultuous period known as the Ottoman Interregnum, characterized by a struggle for control among the sons of Bayezid I after their father’s death. During this period, the empire faced internal strife, with various factions vying for power. Musa, one of the prominent sons, successfully engaged in military campaigns to reclaim authority and suppress opposition. His rule marked a significant turnaround in the political landscape of the empire, as territorial disputes and rival claims were prevalent among the Ottoman princes.

The backing of Mircea I of Wallachia was crucial to Musa's rise. Wallachia, strategically situated on the borders of the Ottoman Empire, was a significant player in regional politics. Mircea's support provided not only military assistance but also legitimized Musa’s claim to the throne. This alliance was beneficial for both parties as it helped secure Musa’s position while also ensuring a buffer against other competitors, notably his brother, Süleyman Çelebi.

Musa’s reign was marked by efforts to stabilize the empire and strengthen its administration amidst the ongoing fragmentation. He focused on restoring order, managing resources, and reclaiming lost territories. His establishment as Sultan set the groundwork for later centralization efforts in the Ottoman Empire, which would eventually lead to its expansion and consolidation in the years to come.