The early history of the Kingdom of Kush, located along the Nile region in what is now northern Sudan, is intertwined with the history of ancient Egypt, with which it was politically allied over several regnal eras. By virtue of its proximity to Egypt, the Sudan participated in the wider history of the Near East, with the most popular episodes being the 25th dynasty and the Christianization of the three Nubian kingdoms Nobatia, Makuria and Alodia in the sixth century. As a result of Christianization, the Old Nubian language stands as the oldest recorded Nilo-Saharan language (earliest records dating to the eighth century) in an adaptation of the Coptic alphabet). While Islam was already present in the Sudanese Red Sea coast and the adjacent territories since the 7th century, the Nile Valley did not undergo formal Islamization until the 14th-15th century, following the decline of the Christian kingdoms. The kingdoms were succeeded by the Sultanate of Sennar in the early 16th century, which controlled large parts of the Nile Valley and the Eastern Desert, while the kingdoms of Darfur controlled the western part of Sudan. Two small kingdoms arose in the southern regions, the Shilluk Kingdom of 1490, and Taqali of 1750, near modern-day South Sudan, but both northern and southern regions were soon seized by Muhammad Ali of Egypt during the 1820s. Resentment toward the oppressive rule of Muhammad Ali and his immediate successors is credited for stirring up resentment toward the Turco-Egyptian rulers that contributed to the Sudanese struggle for independence led by Muhammad Ahmad in 1881.