The earliest silver money in China found through archaeological excavation is from the Warring States period 2000 years ago – imitation cowrie shells made of silver, and silver spade money very similar to hollow handle spade money. In the Tang dynasty there were silver bars (银铤 yinting) and cakes (银饼 yinbing), but limited use of silver as money. In the Song and Jin dynasties, silver and gold money became widespread, and a particular form developed, more or less rectangular, with a large top, a small base, and which narrowed at the waist. This shape continued into the Yuan dynasty. In the Ming dynasty, silver was in common use, and a variety of shapes emerged. In the Qing dynasty, silver ingots continued to be made in a variety of shapes. The influx of foreign silver coins prompted suggestions for a currency reform, to put Chinese silver coins into circulation alongside the foreign coins. In 1887 Zhang Zhidong 张之洞, governor of Guangdong and Guangxi provinces, proposed that a mint be established in Guangzhou (Canton), and purchased minting machinery from Heaton, in Birmingham, UK. In 1890, the Canton Mint issued silver coins, marking the beginning of the move to machine-struck silver coins in China.