Not the well-known one in England, named for the Germanic tribe that predominantly settled (or ruled) there in the early medieval period, but the region in Germany from whence they originally came.
It makes sense after all. There’s a Saxony in Germany, so there should be an Anglia too.
Arrowhead country. The northeastern part of Minnesota between Lake Superior and the Canadian border, shaped roughly like an arrowhead.
The Great North Woods. The part of New Hampshire north of the White Mountains, sometimes considered to include adjacent areas east into Maine and west into Vermont and New York.
The Flat Spot. The largest part of Maine that is without mountains or large hills, roughly a triangle with sides of about 40 miles. Bangor is near the southern edge.
Down East. The coastal areas of Maine east of Penobscot Bay (i.e., Hancock County and Washington County). Sometimes used a synonym for the entire state of Maine by outsiders who don’t know any better.
The Southern Tier. Those counties of New York that border the east-west portion of the boundary with Pennsylvania. Also, but somewhat less common, the “Northern Tier” refers to the adjacent counties on the Pennsylvania side.
Cascadia. British Columbia, Washington, and Oregon, and sometimes considered to include northern California and southeastern Alaska.
Modoc Plateau - the largely flat but very, very rough old lava country in California’s northeast corner. Keintpuash and his followers hid out in the lava-tube terrain there for a long time before surrendering to the Army.
Well known in the UK, but perhaps not outside, is the Black Country,,which is the area west of Birmingham. It’s named so because there were so many factories there in the past that the soot made everything relatively black.
There’s also Dogglerand, an area of the North Sea that was once land, got submerged about 8,500 years ago and still has some prehistoric tools and artefacts on the seabed. It’s not 100% obscure because it’s one of the areas named in the British Isles shipping forecast (as Dogger) which is itself less obscure than you’d think because it’s played at the end of day’s play on Radio Four (after the late book) and some people listen to it as part of a bedtime routine.
The Mosquito Coast in Nicaragua and Honduras is fairly well known but doesn’t appear on most maps. The name doesn’t refer to the insects but to the Miskito Indians who live in the area.
Do you count the gnat line? In Georgia, at least, it’s betweenish Macon and Augusta, east to west. How will you know when you are below the gnat line? You’ll know.
I spent many confused months trying to work out why people were going to noon, or why the government set up a New Deal-type program for 12am, before I discovered it also means the south of Italy.
I always snickered at the various Pasa Tiempo’s in California and the southwest, since ‘passatempo’ is colloquial Italian for dildo. (Yes, both mean “to pass the time.”)
In Spanish and as a single word it means “entertainment” or “hobby” in a general sense, and puzzles such as those you can find in a newspaper in a more limited one.
The Missouri Breaks may qualify. It’s a dramatic area of badlands in northern Montana that was created by the Missouri River, and first noted by the Lewis & Clark Expedition.