They began as a Norse/Germanic earth spirit. Then Tolkien made them as a Semitic people, with a language and history similar to the Jews. But at some point between then and now, dwarves have come to be seen as universally Scottish.
The jovial but grumpy dwarves are Scottish; they also seem to like a drink, although their views on Irn-Bru and deep-fried food have yet to be disclosed.
Tolkien described them as tough, warlike, and lovers of stone and craftsmanship. The origins of Tolkien's Dwarves can be traced to Norse mythology; Tolkien also mentioned a connection with Jewish history and language.
Dwarves were a race of Middle-earth also known as the Khazâd (in their own tongue) or Casari, Naugrim, meaning "Stunted People", and Gonnhirrim, the "Masters of Stone".
The dwarves in films & TV who have Scottish accents are from the Tolkien universe, which I assume is just a natural result of the choices made when developing the character of Gimli. Since LOTR established that dwarves are Scottish, they stuck with that for the Hobbit movies.
Then Tolkien made them as a Semitic people, with a language and history similar to the Jews. But at some point between then and now, dwarves have come to be seen as universally Scottish. They say "Och, laddie" and eat haggis... Even Gimli was played with a Scottish accent.
“When dwarves actually talk, they don't sound Scottish at all,” says Olsen. “They sound like Arabic or Hebrew.” Tolkien's choice here was originally based solely on how different Semitic languages sounded, although later he would admit to accidental similarities between dwarves and Jewish people.
In the books, the dwarves are known for their distinctive language, which Tolkien described as "full of hard consonants and short guttural sounds". This led many readers and later adaptations, such as Peter Jackson's film trilogy, to give the dwarves accents that are similar to those of Scottish or Scandinavian people.
Dwarves were fairly Scottish in the early Forgotten Realms (and possibly Dragonlance, although there's only a few years between the two) novels, and one of Gygax's inspirations for D%D is an early 1950's fantasy novel featuring a Scottish-ish dwarf.
It's a trope started by Peter Jackson's adaptation of Lord of the Rings. The original Lord of the Rings cartoon the dwarves American accents and in Snow White they did too. Since Lord of the Rings, dwarves have Scottish accents.
Now it seems more strange that a Dwarf and a Hobbit have the same accent even though their native tongues are different. Gimli's accent is definitely Welsh, not Scottish.
The Scottish accent has both Germanic and Celtic roots, with each of these language groups having a significant influence on the development of the modern Scottish accent. This can be traced back to Celtic and Germanic settlers in the early middle ages.
Among the many influences on Middle-earth are Celtic sources, namely Irish and Welsh mythology, and the Welsh language. Tolkien's Elves (top left) owe something to the Irish Tuatha Dé Danann, while their Sindarin language is like Welsh.
A dwarf ( pl. : dwarfs or dwarves) is a type of supernatural being in Germanic folklore. Accounts of dwarfs vary significantly throughout history; however, they are commonly, but not exclusively, presented as living in mountains or stones and being skilled craftspeople.
Khuzdul (pronounced [kʰuzˈdul]) is a fictional language created by J. R. R. Tolkien, one of the languages of Middle-earth, specifically the secret and private language of the Dwarves. He based its structure and phonology on Semitic languages, primarily Hebrew, with triconsonantal roots of words.
In Celtic mythology, dragons were believed to be powerful, intelligent creatures with the ability to shape shift and breathe fire. They were often depicted as large, serpentine beasts with wings, and were associated with the elements of earth, air, fire, and water.
They're also very "Viking" like with their love of axes, great beards, and general attitude, but they also have a very semitic influence like on names and their plight to recover their home.
Born in TA 2879, Gimli was the son of Glóin and a nephew of Óin, both former companions of Bilbo Baggins. He was a descendant of Durin the Deathless, father of the first house of the Dwarven people. Gimli was descended from, but was not a member of the royal line.
Abhartach (pronounced [ˈəuɾˠt̪ˠəx]; Irish for 'dwarf'), also Avartagh, is an early Irish legend, which was first collected in Patrick Weston Joyce's The Origin and History of Irish Names of Places (1870). Abhartach should not be confused with the similarly named Abartach, a figure associated with Fionn mac Cumhaill.
The Irish accent demonstrably originates from Gaelic speakers learning English, which is why it sounds so similar to a Highland Scottish accent despite the two regions not having much contact in the past few hundred years.
They came from Germanic mythology more generally; Norse mythology is what we have the most coherent, accessible written records for, so people take it as the baseline. But more broadly, they're Germanic in origin. Moreover, there is a pretty good possibility that they were (at some point) one and the same.
