	In the 16th century, the Ottomans added the Red Sea and Persian Gulf coast (the Hejaz, Asir and Al-Ahsa) to the Empire and claimed suzerainty over the interior. One reason was to thwart Portuguese attempts to attack the Red Sea (hence the Hejaz) and the Indian Ocean. Ottoman degree of control over these lands varied over the next four centuries with the fluctuating strength or weakness of the Empire's central authority. These changes contributed to later uncertainties, such as the dispute with Transjordan over the inclusion of the sanjak of Ma'an, including the cities of Ma'an and Aqaba.