few more notes:
They aren't a certain year (even when you can get them translated). Instead, they go by "dynasties" which can cover many decades.
And even if yours is a particularly older date, it too means next to nothing, as to provenance or dating your site. Those coins can be hundreds of years older than the site they were lost in . They apparently circulated for 100's of years, so some arriving here in the mid to late 1800s, might have dated to the 1700 or 1600's, for instance. I think it was because they were stored in barrells over in China, with no regard for dates, and brought out whenever needed.
There's a humorous story of an archie on a pacific northwest indian mound dig, somewhere in OR or WA, who un-earthed one. It dated to the 1600s I think. So the archie got "all excited" thinking that this somehow showed that the chinese beat the russians or spanish up there, blah blah blah. But the truth is, those durned coins show up, oft-times hundreds of years later, at sites which simply had something from the later 1800's going on.