The Hashemite Kingdom of Hejaz (Arabic: المملكة الحجازية الهاشمية, romanized: Al-Mamlakah al-Ḥijāziyyah Al-Hāshimiyyah) was a state in the Hejaz region of Western Asia that included the western portion of the Arabian Peninsula that was ruled by the Hashemite dynasty. It was self-proclaimed as a kingdom in June 1916 during the First World War, to be independent from the Ottoman Empire, on the basis of an alliance with the British Empire to drive the Ottoman Army from the Arabian Peninsula during the Arab Revolt.
The British government had promised Hussein bin Ali, King of Hejaz, a single independent Arab state that would include, in addition to the Hejaz region, modern-day Jordan, Iraq, and most of Syria, with the fate of the Palestine region (today's Israel and Palestine) being mentioned in more ambiguous terms. However, at the end of the First World War, the Treaty of Versailles turned Syria into a French League of Nations mandate and Iraq, Mandate Palestine and Transjordan into British mandates. Hashemite princes were installed as monarchs under the British mandates in Transjordan and Iraq; this became known as the Sharifian solution.