Diplomacy and commerce during the Ming treasure voyages  The Ming treasure voyages had a diplomatic as well as a commercial aspect. The treasure ships had an enormous cargo of various products. Admiral Zheng returned to China with many kinds of tribute goods, such as silver, spices, sandalwood, precious stones, ivory, ebony, camphor, tin, deer hides, coral, kingfisher feathers, tortoise shells, gums and resin, rhinoceros horn, sapanwood and safflower (for dyes and drugs), Indian cotton cloth, and ambergris (for perfume). They even brought back exotic animals, such as ostriches, elephants, and giraffes. The imports from the voyages provided the large quantities of economic goods that fueled China's own industries. There was so much cobalt oxide from Persia that the porcelain center Jingdezhen had a plentiful supply for decades after the voyages. The fleet also returned with such a large amount of black pepper that the once-costly luxury became a common commodity in Chinese society. There were sometimes so many Chinese goods unloaded into an Indian port that it could take months to price everything. The treasure voyages resulted in a flourishing Ming economy, while boosting the lucrative maritime commerce to an all-time high. The voyages also induced a sudden supply shock in the Eurasian market, where the Chinese maritime exploits in Asia led to disruptions of European imports with sudden price spikes in the early 15th century. The commodities that the ships carried included three major categories: gifts to be bestowed on rulers, items for exchange of goods or payment of goods with fixed prices at low rates (e.g. gold, silver, copper coins, and paper money), and items in which China had the monopoly (e.g. musks, ceramics, and silks). However, the Ming trade enterprise also saw significant changes and developments in which the Chinese themselves began trading and supplying the commodities that were non-Chinese in origin and earlier entirely in the hands of the Indians, Arabs, and other foreigners. For instance, they shipped Southeast Asian sandalwood and Indian pepper to Aden and Dhofar, Indian putchuk and pepper to Hormuz, sandalwood and rice to Mogadishu, and iron cauldrons and pans to Mecca. This highlighted the commercial character of the voyages, in which the Chinese further expanded upon the already large profits from their trade. The impact of the Ming expeditions on commerce was on multiple levels: it established imperial control over local private commercial networks, expanded tributary relations and thereby brought commerce under state supervision, established court-supervised transactions at foreign ports and thereby generate substantial revenue for both parties, and increased production and circulation of commodities across the region.