Sudan (suːˈdæn or suːˈdɑːn; Arabic: السودان‎, as-Sūdān), officially the Republic of the Sudan (Arabic: جمهورية السودان‎, Jumhūrīyat as-Sūdān) is a country in North Africa. It is also sometimes considered part of the Middle East politically though not geographically. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the southwest, Chad to the west and Libya to the northwest. While the population of Sudan predominately descends from both indigenous African groups and Arabs, today most tribes in the country have been Arabized and Arabic and Arab culture predominates. Over 97 percent of the population of Sudan adheres to Islam. The world's longest river, the Nile, divides the country between east and west sides.