Population movements have always played a dynamic role in the transformation of human society throughout history. Indeed, there is not a single phase of history anywhere in the world which has not been related in some way to low or high rates of birth and mortality, to migration and settlement and to their social, cultural, economic, and political effects. The history of the Middle East supplies excellent examples to support this contention. The Muslim calendar begins with an act of migration, that is the hejira of a.d. 622. Migrants going from the countryside to urban centers or fleeing from areas hostile to Islam have always exerted a crucial influence upon the social and political destiny of Muslim countries. The refugees from Spain to North Africa in the fifteenth and sixteenth centuries, the forced migration of Muslims from Russia (the Caucasus and Crimea) in the eighteenth to twentieth centuries, the shift of population in India, Pakistan, and Palestine in the 1940s, to cite just a few examples, have been major factors accounting, at least in part, for the social transformation of the Muslim world in general, and of the Middle East in particular.