The Belgarians were presumably a spacefaring race known to the United Federation of Planets. The Belgarians built the freighter Lionarti, which Carol Abramowitz booked passage on in mid-2376. (SCE eBook: Age of Unreason)

It is possible that "Belgarian" refers to something other than a race (e.g. a specific type of freighter), but without additional references in other sources, it is assumed to be such.