A major trading city of the East African coast, on an island off Tanzania. For three centuries before the arrival of the Portuguese in 1500 it was the leading entrepot on the East African coast. It was first occupied in the 9th century AD, with the earliest settlement being a village of thatched, timber-framed houses. The only industries were iron-working and the manufacture of shell beads. Small quantities of pottery from western Asia and, towards the end of the period, chlorite-schist from Madagascar indicate commercial activity on a modest scale. Prosperity began c 1200, marked by the introduction of coins, widespread use of masonry, and the construction of the mosque. In the 14th century the sultan built a spectacular palace, known as Husuni Kubwa, just outside the town. The establishment of a wealthy Islamic community is identified with the arrival of the so-called Shirazi dynasty which, according to tradition, came from the Persian Gulf. In the 14th and 15th centuries, Kilwa controlled the coast far to the south and grew even more wealthy through its control of the trade in Zimbabwean gold. The arrival of the Portuguese in the Indian Ocean at the end of the 15th century heralded Kilwa's decline.