Where did the adherents go after the demise of Byzantium? Have you become a Muslim? Have you emigrated or been assimilated by Turkey?

Part of it was assimilated by Turks, mainly because the Ottoman Empire at that time implemented the policy that Muslims could not pay taxes or pay less taxes. Many people were attracted by this policy, so all Albanians converted to Islam, and some Serbian-Croats also converted. Now they are called Muslims and become an independent nation. The remaining Serbs, Croats, Macedonians and so on still maintain their religious beliefs.