Christianity in Kosovo has a long-standing tradition dating to the Roman Empire. The entire Balkan region had been Christianized by the Roman, Byzantine and First Bulgarian Empires till 10th century. After the Battle of Kosovo in 1389 until 1912, Kosovo was part of the Muslim Ottoman Empire, and a high level of Islamization occurred. During the time period after World War II, Kosovo was ruled by secular socialist authorities in the Socialist Federal Republic of Yugoslavia (SFRY). During that period, Kosovars became increasingly secularized. Today, 90% of Kosovo's population are from Muslim family backgrounds, most of whom are ethnic Albanians, but also including Slavic speakers (who mostly identify themselves as Gorani or Bosniaks) and Turks.