Palestinian people have a history that is often linked to the history of the Arab Nation. Upon the advent of Islam, Christianity was the major religion of Byzantine Palestine. Soon after the rise of Islam, Palestine was conquered and brought into the rapidly expanding Islamic empire. The Umayyad empire was the first of three successive dynasties to dominate the Arab-Islamic world and rule Palestine, followed by the Abbasids and the Fatimids. Muslim rule was briefly challenged and interrupted in parts of Palestine during the Crusades, but was restored under the Mamluks. After toppling the Mamluk state in 1517, the Ottoman Turks took control of most of the Arab world. Palestine existed within the Ottoman Empire as two districts, also referred to as Sanjaks. The legal origin of citizenship in the Middle East was born of the Ottoman Citizenship Law of 19 January 1869 and the Treaty of Lausanne. Origins Palestinian citizenship developed during the 20th century, starting during the British Mandate era and in different form following the Oslo Peace process, with the former British Mandate definition (before 1925) including the Jews of Palestine and the Arabs of Jordan, and the latter excluding the Arabs of Jordan (at this point part of the sovereign country of Jordan). There has never been a sovereign Palestinian authority that explicitly defined who is a Palestinian, but the term evolved from a geographic description of citizenship to a description of geographic citizenship with an Arab ethnicity. British Mandate period The Treaty of Lausanne, signed on 24 July 1923, came into force on 6 August 1924, and stated that the Ottoman nationals who were "habitually residents" of what became Mandate Palestine "will become ipso facto" Palestinian nationals. Article 7 of the Mandate for Palestine stipulated that the British mandatory power "shall be responsible for enacting a nationality law". The British authority via the structure of the British Mandate of Palestine was directed to "facilitate the acquisition of Palestinian citizenship by Jews who take up their permanent residence in Palestine." Article 15 stated that "No discrimination of any kind shall be made between the inhabitants of Palestine on the ground of race, religion or language. No person shall be excluded from Palestine on the sole ground of his religious belief." The Palestinian Citizenship Order, 1925 was enacted by Britain on 24 July 1925. It granted Palestinian citizenship to "Turkish subjects habitually resident in the territory of