According to Ottoman yearbooks, in 1901, the Kosovo vilayet which encompassed five sanjaks: Skopje, Priština, Prizren, Novi Pazar, and Pljevlja had 964,657 inhabitants; two thirds were Muslims and one third was Christian. The Muslims were primarily Albanians and the Christians were mostly Serbs. The yearbooks, however, are deemed unreliable sources as they, in some districts, did not register the female population, but balanced the numbers against the male population, though it is a well known fact that the number of male heads exceeded the number of female heads throughout this period not only in those lands but in Serbia Proper as well.