Complex sentence: However, the system commonly known as devşirme was soon adopted: in this system children of the rural Christian populations of the Balkans--particularly Albanians, Bulgarians, Serbs, and northern Greeks--were conscripted before adolescence and were brought up as Muslims.
Split into simpler sentences: However, the system commonly known as devşirme was soon adopted. In this system children of the rural Christian populations of the Balkans--particularly Albanians, Bulgarians, Serbs, and northern Greeks--were conscripted before adolescence and were brought up as Muslims.