Muslim scholars in the following centuries, the ancient city-states eventually transformed into Islamic Mogadishu, Berbera, Zeila, Barawa, Hafun and Merca, which were part of the Berberi civilization. The city of Mogadishu came to be known as the City of Islam, and controlled the East African gold trade for several centuries. The Sultanate of Ifat, led by the Walashma dynasty with its capital at Zeila, ruled over parts of what is now eastern Ethiopia, Djibouti and Somaliland. The historian al-Umari records that Ifat was situated near the Red Sea coast, and states its size as 15 days travel by 20 days travel. Its army numbered 15,000 horsemen and 20,000 foot soldiers. Al-Umari also credits Ifat with seven "mother cities": Belqulzar, Kuljura, Shimi, Shewa, Adal, Jamme and Laboo. In the Middle Ages, several powerful Somali empires dominated the regional trade including the Ajuran Sultanate, which excelled in hydraulic engineering and fortress building, the Adal Sultanate, whose general Ahmad ibn Ibrahim al-Ghazi (Ahmed Gurey) was the first commander to use cannon warfare on the continent during Adal's conquest of the Ethiopian Empire, and the Sultanate of the Geledi, whose military dominance forced governors of the Omani empire north of the city of Lamu to pay tribute to the Somali Sultan Ahmed Yusuf. The Harla, an early group who inhabited parts of Somalia, Tchertcher and other areas in the Horn, also erected various tumuli. These masons are believed to have been ancestral to the Somalis ("proto-Somali"). Berbera was the most important port in the Horn of Africa between the 18th–19th centuries. For centuries, Berbera had extensive trade relations with several historic ports in the Arabian Peninsula. Additionally, the Somali and Ethiopian interiors were very dependent on Berbera for trade, where most of the goods for export arrived from. During the 1833 trading season, the port town swelled to over 70,000 people, and upwards of 6,000 camels laden with goods arrived from the interior within a single day. Berbera was the main marketplace in the entire Somali seaboard for various goods procured from the interior, such as livestock, coffee, frankincense, myrrh, acacia gum, saffron, feathers, ghee, hide (skin), gold and ivory. Historically, the port of Berbera was controlled indigenously between the mercantile Reer Ahmed Nur and Reer Yunis Nuh sub-clans of the Habar Awal. According to a trade journal published in 1856, Berbera was described as “the freest port in the world, and the most