In China in and after Northern Sung Dynasty, a coin was minted in a manner that the weight of 10 coins of Tang dynasty called Kai Yuan Tong Bao (or Kai Tong Yuan Bao) equaled 24 zhu, that is to say, 1 ryo (tael), and a weight of the one coin was called 'sen' (銭).
北宋代以降の中国では、開元通宝（開通元寳との説もあり）と呼ばれる唐代の銭貨10枚の質量が24銖すなわち1両という基準でつくられ、1枚あたりの質量を「銭」と呼んだ。