Early records show Vlach population lived in many parts of today's coastal Montenegro and western Bosnia including Republic of Ragusa - today Dubrovnik and Dalmatia because they migrated or where colonized to that area. During the first half of the 13th century, Serbia kingdom started colonizing different Vlach groups on royal and ecclesiastical estates on the eastern part of the Mideast Adriatic coast. While in 13–14th centuries they represented only 1/20 part of the population of that area toward 15 century Vlach population saw a large increase towards 1/3 of the total population. That increase was from 3 factors: fertility, migrations of Vlach from Old Serbia and converting of other nationality into Vlach because Ottomans conquest and their attitude especially towards conquered Serb population that often resisted occupation. During the Ottoman rule to desolated area of Serbia from Kosovo to Smederevo, Ottomans settled large numbers of Vlachs.