Eisen referred the Eiraku-tsuho coins (bronze coins struck in the Ming dynasty) that were used throughout the nation from the Muromachi period to the early Edo period when the currency system by the Edo bakufu was established.
永銭とは、室町時代から、江戸幕府による貨幣制度が整う江戸時代初期まで全国的に流通した永楽通寶銭を指す。