 Complete the following phrase:  Historically Iranians were ruled by an absolute monarchy for several thousand years, at least since the time of the Achaemenid Empire 550 B.C.E. until the Constitutional Revolution in the early 20th century. The Constitutional Revolution in 1906 replaced the absolute monarchy with a constitutional monarchy. The constitution went under several revisions during the following decades. During World War II Iran stayed neutral but in 1941 the Allies the USSR and Great Britain 