The Red River Valley is in Manitoba. The early settlers were Gaelic speaking Highland Scots so it should be hardly surprising that there would be a Gaelic version of this song. There was also a lot of intermarriage between these people and the Native Indians so a Metis connection is also not unreasonable. There is more than one Red River, and just because there is one in Texas does not mean that it was the original venue of the song.
       Slainte,
          Obie