The Yuan Dynasty was ruled by the Mongols. It was founded by Kublai Khan who officially declared the dynasty in the traditional Chinese custom in 1271. It had ruled over most of China, Mongolia and Korea. During this period, Kublai Khan encouraged commercial, scientific and cultural development. He assisted merchants of the Silk Road through development of infrastructure, provided loans to caravans and promote the circulation of bank notes. The dynasty were well-known for its two failed attempts to invade Japan.