Somalia's historical strategic location within the world's oldest and busiest sealanes encouraged the construction of lighthouses to co-ordinate shipping and to ensure the safe entrance of commercial vessels in the nation's many port cities. In times of weak central authority the Somali civilizational matrix of interior cities and port cities was based on a clan formula that saw various clans in fierce competition over natural resources that led to chronic feuding between neighbours. Towers provided the merchant class and the urban population protection against potential raids from the nomadic regions. Stone towers such as the 15th century Almnara tower in Mogadishu and the Jamia tower of Merca were also built for defence.
