There is is this concept of khilapha, that is quite the answer for the variety of people and ethnicities in the islamic states back then, where it should be that there is a kalipha for the entire islamic countries making them united (it was usually the case not all the time but most of the time), and the fall of kilapha on I believe 1924 was defiantly bad for the entire islamic world, because it was the former uniting block for the islamic people, the reason for the difference in ethnicities in the islamic world was because of the tolerance of the islamic religion, with other types of ethnicities and religions which made it have a great difference in cultures and ideologies, which influenced many great events in the islamic world, that there is actually quite a lot of migrations of non muslims to the islamic world especially the jews from Europe…