The national flag of Jordan, officially adopted on 16 April 1928, is based on the 1916 flag of the Arab Revolt against the Ottoman Empire during World War I. The flag consists of horizontal black, white, and green bands, with a red isoceles triangle based at the hoist. The colors are the pan-Arab colors, representing the Abbasid, Umayyad, and Fatimid or Rashidun caliphates. The red triangle represents the Hashemite dynasty, and the Arab Revolt.