Sultan (ˈsʌltən; سلطان , sʊlˈtʕɑːn, solˈtʕɑːn) is a position with several historical meanings. Originally, it was an Arabic abstract noun meaning "strength", "authority", "rulership", derived from the verbal noun سلطة , meaning "authority" or "power". Later, it came to be used as the title of certain rulers who claimed almost full sovereignty (i.e., not having dependence on any higher ruler) without claiming the overall caliphate, or to refer to a powerful governor of a province within the caliphate. The adjectival form of the word is "sultanic", and the state and territories ruled by a sultan, as well as his office, are referred to as a sultanate (سلطنة ). The term is distinct from king (ملك ), though both refer to a sovereign ruler. The use of "sultan" is restricted to Muslim countries, where the title carries religious significance, contrasting the more secular king, which is used in both Muslim and non-Muslim countries. Brunei and Oman are the only independent countries which retain the title "sultan" for their monarchs. In recent years, the title has been gradually replaced by "king" by contemporary hereditary rulers who wish to emphasize their secular authority under the rule of law. A notable example is Morocco, whose monarch changed his title from sultan to king in 1957. Timeline of 11th-century Muslim history The word derives from the Arabic and Semitic root salaṭa "to be hard, strong". The noun sulṭān initially designated a kind of moral authority or spiritual power (as opposed to political power), and it is used in this sense several times in the Qur'an. In the early Muslim world, ultimate power and authority was theoretically held by the caliph, who was considered the leader of the caliphate. The increasing political fragmentation of the Muslim world after the 8th century, however, challenged this consensus. Local governors with administrative authority held the title of amir (traditionally translated as "commander" or "prince") and were appointed by the caliph, but in the 9th century some of these became de facto independent rulers who founded their own dynasties, such as the Aghlabids and Tulunids.