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.
Languages of Scotland
According to the 2001 census Scottish Gaelic has 58,652 speakers (roughly 1% of the population of Scotland). In total 92,400 people aged three and over in Scotland had some Gaelic language ability in 2001. 15,723 of these reside in the Outer Hebrides, where the language is spoken by the majority of the population. There are also large populations of speaker in other parts of the Highlands.