The 1505 expedition of Pêro de Anaia to Sofala led to the establishment of Fort São Caetano, the first permanent Portuguese colony in East Africa. The Capitaincy of Sofala would eventually evolve into the colonial government of Portuguese Mozambique. Although they did not ultimately sail together, Pêro de Anaia's expedition is usually regarded as a squadron of the 7th Portuguese India Armada of D. Francisco de Almeida that left Lisbon a little earlier in 1505 for the Indian Ocean. Prelude Sofala was one of several Muslim Swahili commercial city-states in East Africa under the sway of the Kilwa Sultanate. Around 1489, Sofala had been visited by the Portuguese spy Pêro da Covilhã, who identified it as the principal emporium for the gold trade with the interior kingdom of Monomatapa. The Portuguese crown had been eager to tap into that gold source, and made it a priority for its early Portuguese India Armadas to find the city. In 1498, Vasco da Gama visited several cities along the Swahili Coast, but did not find Sofala. In 1501, captain Sancho de Tovar located the city from the sea, but did not go ashore. Finally, in 1502, Vasco da Gama returned to the area with a new fleet, and, while idling on Mozambique Island, dispatched a detachment of boats under Pedro Afonso de Aguiar to visit Sofala. Arriving at the city, Pedro Afonso de Aguiar sought out an audience with the blind octagenarian sheikh Isuf of Sofala (Yçuf in Barros Çufe in Goes), whom he took to be the ruler of Sofala. In fact, Isuf's authority was ambiguous. Formally, Sofala still belonged to the inland Bantu kingdom of the Monomatapa, and sheikh Isuf was merely the leader of the Swahili community in the city, who paid tribute to Monomatapa for permission to reside and trade there. The community itself was under the legal supervision of the Kilwa Sultanate, and Isuf was originally an appointee of the Sultan of Kilwa. Sheikh Isuf was more of a Kilwan consul than a ruler. Nonetheless, since the usurpation by Emir Muhammad in Kilwa back in 1495, sheikh Isuf had been charting an independent course for his community in Sofala. The Portuguese, with their powerful ships, seemed to offer the key to shaking off Kilwa's authority. At any rate, the elderly sheikh Isuf realized it would be better to make allies rather than enemies out of the Portuguese, and