According to Bernard Lewis, the Janissaries were mainly recruited from the "Slavic and Albanian populations of the Balkans". According to the Encyclopædia Britannica and the Encyclopaedia of Islam, in the early days of the empire all Christians were enrolled indiscriminately. Later, those from Albania, Bosnia, and Bulgaria were preferred. What is certain is that devshirme were primarily recruited from Christians living in the Balkans, particularly Serbs and Bosnians. from Bosnia region, Albanians and Greeks. Well known examples of Ottomans who had been recruited as devshirme include Skanderbeg, Sinan Pasha and Sokollu Mehmed Pasha. The early Ottoman emphasis on recruiting Greeks, Albanians, Bulgarians, and south Slavs was a direct consequence of being centred on territories, in northwestern Anatolia and the southern Balkans, where these ethnic groups were prevalent.