History of Scottish Gaelic
All surviving dialects are Highland and/or Hebridean dialects. Dialects of Lowland Gaelic have become defunct since the demise of Galwegian Gaelic, originally spoken in Galloway, which seems to have been the last Lowland dialect and which survived into the Modern Period. By the 18th century Lowland Gaelic had been largely replaced by Lowland Scots across much of Lowland Scotland. According to a reference in "The Carrick Covenanters " by James Crichton, the last place in the Lowlands where Scottish Gaelic was still spoken was the village of Barr in Carrick: only a few miles inland to the east of Girvan, but at one time very isolated. Crichton gives neither date nor details.
Gigha
Gigha had a vigorous tradition of harping, represented mainly by the family called Mac an Bhreatnaigh (Galbraith), who were active in Gigha and Kintyre, and it is thought that their descendants were in Gigha until at least 1685. In the 1990s it was reported that many of the island's resident spoke Gaelic although the numbers have declined significantly in recent years.