Sudan, officially the Republic of the Sudan, is an Arab republic in the Nile Valley of North Africa, bordered by Egypt to the north, the Red Sea, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the southwest, and Chad to the west and Libya to the northwest. It is the third largest country in Africa. The Nile River divides the country into eastern and western halves. Its predominant religion is Islam.
Sudan was home to numerous ancient civilizations, such as the Kingdom of Kush, Kerma, Nobatia, Alodia, Makuria, Meroë and others, most of which flourished along the Nile River. During the predynastic period Nubia and Nagadan Upper Egypt were identical, simultaneously evolved systems of pharaonic kingship by 3300 BC. By virtue of its proximity to Egypt, the Sudan participated in the wider history of the Near East inasmuch as it was Christianized by the 6th century and Islamized in the 7th. As a result of Christianization, the Old Nubian language stands as the oldest recorded Nilo-Saharan language (earliest records dating to the 9th century). During Classical Antiquity, modern-day Sudan was known as Ethiopia.