Military history of the Crusader states
The Seljuk–Crusader War began when the First Crusade wrested territory from the Seljuk Turks during the Siege of Nicaea in 1097 and lasted until 1128 when Zengi became atabeg of Aleppo. At the latter date, the chief threat to the Crusaders from the east and north became the Zengids. The conflict was generally fought between European Crusaders and the Seljuk Turks and their vassals. The Muslim Syrian emirates occasionally allied themselves with the Christians against rival states.
Temple Mount
The Crusader period began in 1099 with the First Crusade's capture of Jerusalem. After the city's conquest, the Crusading order known as the Knights Templar was granted use of the Dome of the Rock on the Temple Mount. This was probably by Baldwin II of Jerusalem and Warmund, Patriarch of Jerusalem at the Council of Nablus in January 1120, which gave the Templars a headquarters in the captured Al-Aqsa Mosque. The Temple Mount had a mystique because it was above what were believed to be the ruins of the Temple of Solomon. The Crusaders therefore referred to the Al Aqsa Mosque as Solomon's Temple, and it was from this location that the new Order took the name of "Poor Knights of Christ and the Temple of Solomon", or "Templar" knights.