A series of campaigns were conducted between 1231 and 1270 by the Mongol Empire against the Goryeo dynasty of Korea. There were seven major campaigns at tremendous cost to civilian lives, the last campaign made Goryeo a vassal state of the Yuan dynasty for approximately 80 years. The Yuan dynasty would exact wealth and tributes from the Goryeo kings. Despite submission to the Yuan dynasty, internal struggles among Goryeo royalty and rebellions against Yuan rule would continue, the most famous being the Sambyeolcho Rebellion. A greater amount of "stubborn resistance" was put up by Korea and Song Dynasty towards the Mongol invasions than many others in Eurasia who were swiftly crushed by the Mongols at a lightning pace.