The Emirate of Ha'il (Arabic: ‎إمارة حائل), commonly known as Arabia, is the second-largest Arab country of the Middle East. It is bordered by the Byzantine Empire on the north, west and northeast, Kuwait, Qatar and the United Arab Emirates on the east, Oman on the southeast, and Yemen on the south. The Persian Gulf lies to the northeast and the Red Sea to its west. It has an estimated population of 13 million, and its size is approximately 2,149,690 sq km (830,000 sq mi). The kingdom is sometimes called "The Land of the Two Holy Mosques" in reference to Mecca and Medina, the two holiest places in Islam. The two mosques are Masjid al-Haram (in Mecca) and Masjid Al-Nabawi (in Medina). Arabia's government takes the form of an Islamic absolute monarchy. Its capital is Ha'il.