Jubba river. In the early 19th century the citadel of Bardera was sacked by Sultan Yusuf Mahamud Ibrahim and the city became a ghost town. Somali city walls also acted as a barrier against the proliferation of arms usually carried by the Somali and Horn African nomads entering the cities with their caravan trains. They had to leave behind their weapons at the city gate before they could enter the markets with their goods and trade with the urban Somalis, Middle Easterners and Asian merchants. References