By the 16th century, however, the expansion of European trade – albeit restricted to islands near Guangzhou such as Macau – spread the Columbian Exchange of crops, plants, and animals into China, introducing chili peppers to Sichuan cuisine and highly productive maize and potatoes, which diminished famines and spurred population growth. The growth of Portuguese, Spanish, and Dutch trade created new demand for Chinese products and produced a massive influx of Japanese and American silver. This abundance of specie remonetized the Ming economy, whose paper money had suffered repeated hyperinflation and was no longer trusted. While traditional Confucians opposed such a prominent role for commerce and the newly rich it created, the heterodoxy introduced by Wang Yangming permitted a more accommodating attitude. Zhang Juzheng's initially successful reforms proved devastating when a slowdown in agriculture produced by the Little Ice Age joined changes in Japanese and Spanish policy that quickly cut off the supply of silver now necessary for farmers to be able to pay their taxes. Combined with crop failure, floods, and the Great Plague, the dynasty collapsed before the rebel leader Li Zicheng, who was himself defeated shortly afterward by the Manchu-led Eight Banner armies who founded the Qing dynasty.