https://en.wikipedia.org/wiki/McMahon%E2%80%93Hussein_correspondence

The McMahon–Hussein correspondence[a] is a series of letters that were exchanged during World War I, in which the government of the United Kingdom agreed to recognize Arab independence in a large region after the war in exchange for the Sharif of Mecca launching the Arab Revolt against the Ottoman Empire.[2][3] The correspondence had a significant influence on Middle Eastern history during and after the war; a dispute over Palestine continued thereafter