Nubia is a region along the Nile river located in what is today northern Sudan and southern Egypt. It was one of the earliest civilizations of ancient Northeastern Africa, with a history that can be traced from at least 2000 B.C. onward (through Nubian monuments and artifacts, as well as written records from Egypt and Rome), and was home to one of the African empires. There were a number of large Nubian kingdoms throughout the Postclassical Era, the last of which collapsed in 1504, when Nubia became divided between Egypt and the Sennar sultanate, resulting in the Arabization of much of the Nubian population. Nubia was again united within Ottoman Egypt in the 19th century, and within the Kingdom of Egypt from 1899 to 1956.