The Osmanlis did not as yet exist, and their ancestors, the Seljukians, were already closely connected in blood with the races of Islam. The chiefs of this people, such as Gayaseddin-Keikosrev, in 1237, freely intermarried with Arab women. They did better still; for Aseddin, the mother of another line of Seljukian princes, was a Christian. In all countries the chiefs watch more jealously than the common people over the purity of their race; and when a chief showed himself so free from prejudice, it is at least permissible to assume that his subjects were not more scrupulous. As the continual raids of the Seljukians offered them every opportunity to seize slaves throughout the vast territory which they overran, there is no doubt that, from the thirteenth century, the ancient Oghuz stock, with which the Seljukians of Rûm claimed a distant kinship, was permeated to a great extent with Semitic blood. From this branch sprang Osman, the son of Ortoghrul and father of the Osmanlis. The families that collected round his tent were not very numerous. His army was no more than a robber-band; and if the early successors of this nomad Romulus were able to increase it, they did so merely by following the practice of the founder of Rome, and opening their tents to anyone who wished to enter. It may be assumed that the fall of the Seljukian Empire helped to send recruits of their own race to the Osmanlis. It is clear that this race had undergone considerable change; besides, even these new resources were not enough, for from this time the Turks began to make systematic slave-raids, with the express object of increasing their own population. At the beginning of the fourteenth century, Urkan, at the instance of Khalil Chendereli the Black, founded the Guard of Janissaries. At first these were only a thousand strong. But under Mohammed IV the new guard numbered 140,000; and as up to this time the Turks had been careful to fill up the ranks only with Christian children taken from Poland, Germany, and Italy, or from European Turkey itself, and then converted to Islam, there were in four centuries at least 5000 heads of families who infused European blood into the veins of the Turkish nation.