 The "Kōchōsen" Japanese system of coinage became strongly debased, with its metallic content and value decreasing.By the middle of the 9th century, the value of a coin in rice had fallen to 1/150th of its value of the early 8th century.By the end of the 10th century, compounded with weaknesses in the political system, this led to the abandonment of the national currency, with the return to rice as a currency medium.