The discovery in 1526 of the Iwami Ōmori silver deposits enabled Japan to become, by the 1540s, China's largest supplier of silver. This status was surpassed only in the 1570s, when large amounts of South American silver began to be delivered to southeast China via Manila. Despite the popularity of silver in the conduct of foreign trade, until the end of the sixteenth century it rarely played a part in Japanese domestic transactions. Even in Kyoto, capital of medieval Japan, it was gold, not silver, that was used for gifts and remittances. When for political reasons the Mōri clan donated the Ōmori silver mine to the court and Muromachi Bakufu, the flow of silver into Kyoto commenced in earnest. During the late 1560s gold assumed the characteristics of a fully functional currency, a development that paved the way for silver too, by the end of that decade, to become a major form of currency for domestic transactions involving imported items. During the 1570s usage of silver expanded to include other types of transactions. The 1580s and 1590s witnessed its firm establishment as currency, thus laying the foundation for the role of Kyoto in the early modern sphere of silver currency usage.