According to this article: In the Late Middle Merethic Era, the Velothi Mountains were settled by the Dwemer, who created cities beneath the mountain range. Presumably these cities followed the fate of their counterparts in Morrowind and Hammerfell and now lie deserted, but no further information on the cities exists.
Velothi Mountains is on the border of Skyrim and Morrowind. Markarth (built on a Dwemer city) and other Dwemer ruins I've found are in the west of Skyrim, on the border with High ROck.
The Dwemer, and all the elves, predate the Nords on Tamriel.
The only known Dwemer to have settled outside Morrowind (Rourken Clan) left Morrowind in the year 416 of the First Era, so more than four centuries after Ysgramor and his 500 companions killed pretty much all Elves upon their return to Skyrim, and drove what remained underground (Falmer). Dwemer ruins should have been Falmer ruins.
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