If you’re interested in ancient tales set in the British Isles, and you’ve already read Beowulf, you might turn to the Irish Táin Bó Cúailnge or the Welsh Mabinogion. There’s a certain structure pretty common to epic stories from thousands of years ago; you can still find basically the same thing in super hero comics. There’s someone extraordinary who performs amazing feats, sometimes besting other superhuman characters. You find this not just in stories set in Britain, of course, but in Gilgamesh, the Odyssey, the Nibelungenlied, the Mahabharata, and more.
More than the basic elements of plot, though, you can find something else in the ancient books: ancient language. If you’re a modern-day author and you want to set your story in an authentically medieval time — or an authentic-sounding pre-technological fantasy world — you might find some good ideas, turns of phrase, and obsolete words in the old stories.
The Maginogion is a set of stories first written down in the 1100s in Wales — the stories themselves are much older, and before that had been passed along by retelling. A peek inside will reveal the word “cantrev.” Spell checkers weren’t very reliable back then, so “cantrev” also shows up as “cantref” and “canthrif,” but they’re the same thing. And that same thing is an administrative concept; it’s a division of a county (or a “shire”).
“Cantrev” is a compound Welsh word put together from “cant” (a hundred) and “tref” (a town). The “hundred”, in this case, doesn’t refer to the number; in England at that time a “hundred” was an indistinct measurement of an area. Nobody is quite sure where that word came from, but William Stubbs wrote a history book in the 1870s with what’s considered the best guess: “It has been regarded as denoting simply a division of a hundred hides of land; as the district which furnished a hundred warriors to the host; as representing the original settlement of the hundred warriors; or as composed of a hundred hides, each of which furnished a single warrior.” And, naturally, “hide” has a special meaning there; in ancient England a “hide” was the amount of land that could be tilled by one plow in one year.
None of this is particularly relevant today, except that the word “cantrev” is, thanks to those modern-day authors, having a bit of a resurgence. You can find it, for example, in Adam Robots, a 2013 book of short stories by Adam Roberts: “So, the land there is thickly forested to the north and the forest grows even more thickly and densely to the south. This southern cantrev of forest is so very dense, indeed, that there is no other place in the world with trees of such height or magnificence or profusion.”
It might be considered a cheap authoring trick to toss in a word that you’re quite aware not one of your readers will know without looking up. It could be an attempt to instill the story with an otherworldly aura of course…but maybe it’s just flosculation.