The Mamluk Sultan who defeated the Mongol hordes at Ain Jalut in northern Palestine, and eliminated most of the last Crusader strongholds on the Syrian coast. Born in Qippchaqe, territory near Black Sea, Rukn Uddin Baybrus was sold as a slave by the Mongol invaders to Salih Najm uddin Ayyub of Egypt. He became Sultan's bodyguard. His first victory was against the Crusader's army led by Louis IX of France, in 1250, who was captured by him. Baybrus was also victorious against the Mangol Sultan at Ayn Jalut, near Damascus, in 1260 and from 1265 to 1271 Baybrus conducted annual raids against the Crusaders. He captured Haifa, Atlit, Jaffa and Antioch, in 1268, and his victories at other strongholds of the Crusader's sealed their fate. During the 17 years of his reign, he fought nine battles against the Mongols. He dealt firmly with the assassins and seized their major strongholds among 1271 and 1273. In 1276, Baybrus defeated the Seljuqs and sent expeditions against Libya and Nubia. He sent ambassadors to Sicily, Naples, Leon and Castile and to Constantinople, Byzantine Empire. Sultan Baybrus built canals, harbours and established a fast postal service between Cairo and Damascus. The establishment of the postal system necessitated building and improvement of infrastructure namely roads, bridges, way-stations for rest and changing horses etc. This contributed to security throughout the country. Rukn Uddin Baybrus (full name, Baybar I Al Malik Az Zahir Rukn Uddin Baybrus As Salihi) was buried in Damascus under the dome of the present Az-Zahiriyah library, established by him.