In the year 1173 CE T?r?nsh?h, the brother of the Ayyubid founder ?al?? al-D?n, conquered the Yemeni coast and southern highlands, taking control of the strategic and lucrative port of Aden. Among his mercenary officers was Shams al-D?n ‘Al? ibn Ras?l, who fathered four sons. One of these sons, ‘Umar, was left in charge when the last Ayyubid monarch left Yemen in 1229. Three years later ‘Umar took the name of al-Malik al-Man??r and initiated a Rasulid dynasty, soon recognized by the Abbasid caliph in Baghdad, that would last a little over two centuries. This paper examines the formation of the Rasulid state, both in terms of the extension of an administrative system created by the Ayyubids and the transition to make the port of Aden a major entrepôt along the Red Sea/Indian Ocean trade network. The Rasulid state benefited from the turmoil elsewhere in the region due to the remaining crusader conflict and Mongol invasions. As wealthy patrons, the Rasulid sultans attracted Islamic scholars and supported the building of major mosques and madrasas. The Rasulid sultans maintained active relations with the Mamluks in Egypt, at times competing for control of Mecca. The main threat to Rasulid rule was from the Zaydi imams in the north, who were supported by tribal groups that rebelled against Rasulid taxation and political control. Based on the wealth of Yemeni chronicles and administrative texts, this paper assesses what was unique in the formation of the Rasulid state and what was shared with the rise of the Mamluks in Egypt.