Kilwa at its height under Sultan al-Hasan ibn Sulaiman

At the end of the 13th century power in Kilwa passed from the Shirazi line, which claimed descent from a legendary prince of Shiraz, to the Mahdali, a family of Yemeni Arab origin. Al-Hasan, a grandson of its founder, had studied in Aden; he was on pilgrimage in Mecca when his father died, and took the throne on his return, after his brother Daud had ruled for two years. Kilwa’s wealth came from its hold on Sofala, the port through which gold and ivory from the interior — the realm of Great Zimbabwe — reached the Indian Ocean. Al-Hasan’s copper coins circulated widely — one has been found as far away as Great Zimbabwe — and he is the only ruler of Kilwa known to have struck gold coins. He also brought the island of Mafia back under Kilwa’s rule.

Outside the town, on a high bluff above the sea, he built Husuni Kubwa — a court for trade, a residence of more than a hundred rooms, a pavilion and an octagonal pool — whose domes and vaults brought new forms into Swahili architecture; it was never finished and was abandoned after his death. The domed extension of the Great Mosque is also attributed to his reign. Ibn Battuta, who sailed down the coast from Mogadishu by way of Mombasa in 1331 according to the Rihla, or in 1329 according to the revised chronology of Gibb and Dunn (the chronology of these years of his travels is disputed), called Kilwa a very fine and substantially built town and heard there that gold dust reached Sofala from a land a month’s journey inland. He saw the sultan give the clothes off his back to a beggar, and noted that he set aside a fifth of the booty from his raids on the ‘heathen’ mainland for pious works. The ruins of Kilwa Kisiwani have been a UNESCO World Heritage Site since 1981.