Palestine was under the rule of the Eastern Roman Emperors since 400 AC and until it was conquered by Omar Ibn Al-Khattab, who was given the keys of Jerusalem from Patriarch Safronios in 638 AC. The city then remained under Islamic-Arab rule until the Crusaders captured it in 1099 AC. Christian rule lasted until 1187 AC when Salah Eddin reconquered the city, which then was ruled by the Ayyubids until being recaptured by the Crusaders in 1129. Some 15 years later, the Arabs regained Jerusalem and the city remained in their handsuntil 1917.
In 1517, Turkish Sultan Selim I conquered Jerusalem and Palestine and incorporated both into the
Ottoman Empire, which remained in control until the British occupation in 1917, with the exception of
a short period of Egyptian rule (from 1831 until 1840). In the course of World War I, the Ottoman
forces capitulated in Jerusalem on 9 December 1917 and mayor Selim Effendi Al-Husseini surrendered to the allied forces led by British Gen. Edmond Allenby, who officially entered the city two days later and established the British military administration in Jerusalem. In April 1920, the San Remo Conference awarded administration of the former Turkish territories of Syria and Lebanon to France, and Palestine, Transjordan and Mesopotamia (Iraq) to Britain. On 24 July 1922, the League of Nations Council approved the Mandate for Palestine without the consent of Palestinians (The terms of the Mandate became official on 29 Sept. 1923, until which time British military rule remained in place).