<P> The most important artefacts recovered from the Monument are the eight Zimbabwe Birds . These were carved from a micaceous schist (soapstone) on the tops of monoliths the height of a person . Slots in a platform in the Eastern Enclosure of the Hill Complex appear designed to hold the monoliths with the Zimbabwe birds, but as they were not found in situ it cannot be determined which monolith and bird were where . Other artefacts include soapstone figurines (one of which is in the British Museum), pottery, iron gongs, elaborately worked ivory, iron and copper wire, iron hoes, bronze spearheads, copper ingots and crucibles, and gold beads, bracelets, pendants and sheaths . </P> <P> Archaeological evidence suggests that Great Zimbabwe became a centre for trading, with artefacts suggesting that the city formed part of a trade network linked to Kilwa and extending as far as China . Copper coins found at Kilwa Kisiwani appear to be of the same pure ore found on the Swahili coast . This international trade was mainly in gold and ivory; some estimates indicate that more than 20 million ounces of gold were extracted from the ground . That international commerce was in addition to the local agricultural trade, in which cattle were especially important . The large cattle herd that supplied the city moved seasonally and was managed by the court . Chinese pottery shards, coins from Arabia, glass beads and other non-local items have been excavated at Zimbabwe . Despite these strong international trade links, there is no evidence to suggest exchange of architectural concepts between Great Zimbabwe and centres such as Kilwa . </P> <P> Causes for the decline and ultimate abandonment of the site around 1450 have been suggested as due to a decline in trade compared to sites further north, the exhaustion of the gold mines, political instability and famine and water shortages induced by climatic change . The Mutapa state arose in the fifteenth century from the northward expansion of the Great Zimbabwe tradition, having been founded by Nyatsimba Mutota from Great Zimbabwe after he was sent to find new sources of salt in the north; (this supports the belief that Great Zimbabwe's decline was due to a shortage of resources). Great Zimbabwe also predates the Khami and Nyanga cultures . </P> <P> The first European visit may have been made by the Portuguese traveler António Fernandes in 1513 - 1515, who crossed twice and reported in detail the region of present - day Zimbabwe (including the Shona kingdoms) and also fortified centers in stone without mortar . However, passing en route a few kilometres north and about 56 km (35 mi) south of the site, he did not make a reference to Great Zimbabwe . Portuguese traders heard about the remains of the ancient city in the early 16th century, and records survive of interviews and notes made by some of them, linking Great Zimbabwe to gold production and long - distance trade . Two of those accounts mention an inscription above the entrance to Great Zimbabwe, written in characters not known to the Arab merchants who had seen it . </P>

Factors that led to the decline of the great zimbabwe state