In 621 Emperor Gaozu replaced a monetary system that had continued virtually unchanged for almost 750 years. The coins were inscribed with Chinese characters that read kai yuan (roughly "new beginning) from top to bottom, and tong bao ("circulating wealth"). This describes both the function of the coins, and the intentions of Gaozu to mark the start of a new age for China. In fact, Gaozu's new coinage system would outlast the Tang dynasty by more than a millennium, as the decimal system on which the coins were measured would remain the monetary standard into the nineteenth century.