original question: Which system of nobility is the first one that has the rank of [Sultan]?
answer: sultanate of rum
answer type: System of nobility.
auxiliary information: Sultan is a noble title with several historical meanings. Originally, it was an Arabic abstract noun meaning "strength", "authority", "rulership", derived from the verbal noun ÿ≥ŸÑÿ∑ÿ© sul·π≠ah, meaning "authority" or "power". Later, it came to be used as the title of certain rulers who claimed almost full sovereignty in practical terms, albeit without claiming the overall caliphate, or to refer to a powerful governor of a province within the caliphate. The dynasty and lands ruled by a sultan are referred to as a sultanate. A feminine form of sultan, used by Westerners, is sultana or sultanah; however, this styling misconstrues the roles of wives of sultans. In a similar usage, the wife of a German field marshal might be styled Feldmarschallin. The rare female leaders in Muslim history are correctly known as "sultanas". However, in the Sultanate of Sulu, the wife of the sultan is styled as the "panguian". Among those modern hereditary rulers who wish to emphasize their secular authority under the rule of law, the term is gradually being replaced by king and Datu in Maranao.
Of the system of nobilities, which is the first one that has the rank of [Sultan]?