Swiss Ephemeris is the high precision ephemeris developed by Astrodienst, largely based upon the DExxx ephemerides from NASA's JPL, but JPL's data is heavily compressed (97 MB instead of 2788 MB).
It covers the time range between 13201 BC and 17171 AD. The makers claim that SwissEph positions never differ more than 0.001 arcseconds apart from JPL's calculation.