I'm not even sure which county in Scotland my Reas came from, Slogger. I'm just going by information I've found that suggests Hugh Rea and James Rea of County Down, Northern Ireland (who are both found on the Hamilton Estate rent rolls in 1681 and 1688) may have come from anywhere in Aryshire, Renfrewshire, Wigtownshire, Dumfriesshire or Kirkcudbright. So, I'm researching all these areas, plus others where I found Rea/Rae families living in the 17th century. Currently, I believe my line emmigrated to County Down sometime prior to 1631, as there was a William, James and Gilbert Rea found on the 1631 muster roll for County Down, which was taken in Bangor.
Anyway, the "Plantation Period" was the 1600s, when James Hamilton and other wealthy Scots landowners bought estates in Northern Ireland and then recruited men from the lowlands of Scotland and from England to occupy and farm these lands. The idea was to "plant" loyal subjects of King James I in Northern Ireland in order to pacify the Irish and to subjugate them, hence the term "Plantation." We can see how well that's turned out. Oddly enough, the same term was used in the southern United States to describe the estates founded by Scots-Irish immigrants of the 18th century, though the circumstances were entirely different.
Gary