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 in censuses
Iceland has been a very isolated and linguistically homogeneous island historically, but has nevertheless beheld several languages. Gaelic was native to many of the early Icelanders, the Icelandic or Norse language however prevailing, albeit absorbing Gaelic features. Later, northern trade routes brought German, English, Dutch, French and Basque. Some merchants and clergymen settled in Iceland throughout the centuries, leaving their mark on culture, but linguistically mainly trade, nautical or religious terms. Excluding these and Latin words, Icelandic has altered remarkably little since settlement, the island's residents living in seclusion.