Etymological geography, or, if you prefer, geographical etymology:
Language Log had an interesting post about it (link). For example:
Of course, as pointed out in a later amendment, it isn't really intended as a scholarly work and it is a fun idea.
—Ceci n'est pas un seing.
It looks like a cool book. Part of me wishes it was accurate, but if it was accurate, it would be a lot less interesting. The etymologies of many place names are unknown.
I suppose the name "Great Land of the Tattooed" is supposedly an ancient name for Great Britain. I'd not have thought it especially accurate nowadays.
The Online Etymology Dictionary says that the British were called Prittanoi in Greek, which is said to mean "tattooed people." But this is the thing. Is the English word Britain really derived from Greek Prittanoi, and did Greek Prittanoi really mean "tattooed people"? The Online Etymology Dictionary uses a lot of sources, but we don't know which source this is from to check it. And the phrase said to mean indicates that it is not certain.
The OED suggests that
But it's one of a few possible etymologies. The OED says nothing about tattoos.