Hashemite Kingdom of Jordan
Who & why: the March 1946 Treaty of London ended the British Mandate, and Emir Abdullah I was proclaimed king of the Hashemite Kingdom of Transjordan two months later. The Hashemite dynasty descends from the Sharifate of Mecca, through Sharif Hussein bin Ali, who led the 1916 Arab Revolt. In the 1948 war Transjordan took control of the West Bank, annexing it in 1950 (the kingdom was renamed Jordan the following year); Jordan formally relinquished its legal and administrative claims to the West Bank in 1988. The kingdom has been a comparatively stable constitutional monarchy since independence.
What it represents: black, white, and green horizontal bands (representing the Abbasid, Umayyad, and Fatimid caliphates respectively) with a red chevron bearing a white seven-pointed star at the hoist, a design descended from the 1916 Arab Revolt flag and in use, unchanged, since 1928.