Complex sentence: A site with natural defences was a typical location for Crusader castles and steep slopes provided Krak des Chevaliers with defences on all sides bar one, where the castle's defences were concentrated.
Split into simpler sentences: A site with natural defences was a typical location for Crusader castles. Steep slopes provided Krak des Chevaliers with defences on all sides bar one, where the castle's defences were concentrated.