The change of Eastern Thrace, one of the most important settlement centers of Rumeli immigrants.According to the "1520-35" cadastral registers at the beginning of the 16th century, the Nation of Islam constituted 56% of the population in Eastern Thrace. Later, the Muslims of Eastern Thrace migrated to the interior of Rumelia for various reasons and there was a sharp population decline in Eastern Thrace. The non-Muslim population reached the overwhelming majority in this process. So much so that in the first Ottoman census "1831" Muslims constituted 30% of the population in Eastern Thrace. There is no reliable data about the intervening 300 years. 93 In the census conducted after the first wave of immigration after the "1877-78" War, the Muslim population seems to have increased to 39% in "1893". In 1906, when Danube migrations slowed down, there was a 43% Muslim population in Eastern Thrace. After the Balkan wars "1912-13", the Muslim population increased to 55% with the second wave of immigration, and approximately 4 centuries later, the Muslim population became the majority in the region with the influx of immigrants. It reached 99% with the Turkish-Greek population exchange of 1923-27.