Complex sentence: Leipzig (1882) It is thought that during the 17th century, like in the whole surrounding region, its inhabitants were converted from "Paulicianism" to Islam and since then were called "Pomaks" (Muslim Bulgarians) afterwards.
Split into simpler sentences: Leipzig (1882) It is thought that during the 17th century, like in the whole surrounding region, its inhabitants were converted from "Paulicianism" to Islam. Since then they began to be called "Pomaks" (Muslim Bulgarians) afterwards.