Not a lot is known about Usman, who founds that first kingdom in the Anatolian Peninsula. It's a Sunni Islamic empire. In fact, the leader is eventually named a caliph. The ruling class of this empire is Turkish. Now, one of their distinguishing characteristics is what's known as the Devshirme system, in which the sultan, the emperor, would have a personal army of what could be called slaves, these janissaries. These janissaries were actually Christian boys taken at a young age and then indoctrinated into the janissary system. The reason why I said you can kind of call them slaves is that although they were forced to become janissaries and taken from their families, they were given many privileges, and over time, many of these janissaries became some of the most notable figures in the Ottoman Empire, some of them even becoming the Grand Vizier, effectively ruling over the empire.