During the fifteenth century the Ottoman Turks managed to organize themselves on the territory of what is now Turkmenistan and Uzbekistan, and they used the opportunity that the Mongol Empire has fallen apart, so they moved westward in a military campaign to take over territories, first in the Middle East, which they did with ease, and than they reached the Byzantine Empire. They didn't found it very easy to take down the Byzantine Empire but with with a very well military strategy and the great cavalry they did manged to put an end to the Eastern Roman Empire and capture Constantinople, the most important place of Orthodox Christianity. After this they continued with their conquest in the Balkans, and one by one managed to conquer pretty much all of the peninsula. They were finally stopped at Vienna, where large united armies of Central and Western Europe organized themselves in order to stop the conquest of the Ottomans and the Islam. The Ottomans also managed to spread eastwards and conquer the territory of what has once been Persia, and also the coastal regions of North Africa.