Complex sentence: He was a younger brother of Theodor and Asen, who lead the uprising of the Bulgarians and Vlachs against the Byzantine Empire in 1185 which ended with the restoration of the independence of Bulgaria.
Split into simpler sentences: He was a younger brother of Theodor and Asen who lead the uprising of the Bulgarians and Vlachs in 1185. The uprising ended with the restoration of the independence of Bulgaria.