Complex sentence: The Bosnian Crusade (1235--1241) was a campaign against the Bosnian church, depicted as a campaign against Catharism (Bogomilism) although possibly motivated by a Hungarian territorial expansion.
Split into simpler sentences: The Bosnian Crusade was a campaign against the Bosnian church and depicted as a campaign against Catharism (Bogomilism). However, it was also possibly motivated by a Hungarian territorial expansion.