The United Kingdom promised King Ali of Hejaz a single independent Arab state that would include modern day Syria, Iraq, Palestine and Jordan in addition to the Hejaz region. However, at the end of the First World War, the Treaty of Versailles turned Syria into a French protectorate while Iraq, Palestine and Transjordan became British Protectorates. The relations with the British Empire further deteriorated when Zionist Jews were allowed to move to Palestine. The newly independent kingdom had a brief life and then was invaded in 1924 by the neighbouring Sultanate of Nejd under a resurgent House of Saud. Nejd was much stronger and its military more advanced, and Hejaz tried to defend itself during the year-long war. In 1925, the kingdom collapsed and was conquered by Nejd, creating the Kingdom of Hejaz and Nejd.