The Muslim West
The establishment of a defensive system.
Fortifications in the Muslim West were erected for two reasons: to defend borders and to consolidate power over conquered lands that were continually threatened by internal conflicts. Construction of defensive structures was initially sporadic and designed to suppress rebellious local populations. More complex defensive systems were subsequently developed throughout the West under Almohad rule, and were later adapted to counter new attacking strategies that employed catapults, battering rams and assault towers.
Merida Citadel

Hegira 220 / AD 835
Umayyad of al-Andalus, Emirate period
Merida, Badajoz, Spain
Unlike isolated fortifications, the defence system at Merida was based on complementary constructions such as multiple enclosures and strong towers and walls.