During what dynasty did the wuzhu stop being the standard coin?
In 144 BC Emperor Jing abolished private minting in favor of central-government and commandery-level minting; he also introduced a new coin. Emperor Wu introduced another in 120 BC, but a year later he abandoned the ban liangs entirely in favor of the wuzhu (五銖) coin, weighing 3.2 g (0.11 oz). The wuzhu became China's standard coin until the Tang dynasty (618–907 AD). Its use was interrupted briefly by several new currencies introduced during Wang Mang's regime until it was reinstated in 40 AD by Emperor Guangwu.