 Bronze tools and gold was traded with the Koreans while Chinese traded bronze mirrors, bells, swords, spearheads, rice and gold ores mined in the Japanese mountains.From the end of the 7th century to the 8th century, Japan introduced various sociopolitical systems imported from Tang China in order to create a centralized government based on the medieval Japanese "ritsuryo" code.The Yamato government began minting coins in 708 AD.