 City walls were established around the coastal cities of Merka, Barawa and Mogadishu during the Ajuran Empire period to defend the Ajuran cities against powers such as the Portuguese Empire.During the Adal Age, many of the inland cities such as Amud and Abasa in the northern part of Somalia were built on hills high above sea level with large defensive stone walls enclosing them and Zeila the Adal capital was protected by Citadels.The Bardera militants during their struggle with the Gobroon Dynasty had their main headquarters in the walled city of Bardera that was reinforced by a large fortress overseeing the Jubba river.