Complex sentence: It has been suggested that Maiden Castle was occupied as a Roman military outpost or fort and the settlement discontinued, as there is no known fort in the area and it was not uncommon for hill forts in the southwest to have been occupied by Roman forces.
Split into simpler sentences: It has been suggested that Maiden Castle was occupied as a Roman military outpost and the settlement discontinued. A Roman fort on the site has been suggested as there is no known fort in the area and it was not uncommon for hill forts in the southwest to have been occupied by Roman forces.