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.
Inner Hebrides
There have been speakers of Goidelic languages in the Inner Hebrides since the time of Columba or before, and the modern variant of Scottish Gaelic ("Gàidhlig") remains strong in some parts. However, the Education (Scotland) Act 1872 led to generations of Gaels being forbidden to speak their native language in the classroom, and is now recognised as having dealt a major blow to the language. Children were being beaten for speaking Gaelic in school as late as the 1930s. More recently the Gaelic Language (Scotland) Act was enacted by the Scottish Parliament in 2005 in order to provide continuing support for the language.