Correct me if I'm wrong but don't the Hist predate Nirn?
That is a matter of some controversy. A particular reading of the Anuad suggests that the current inhabitants of Nirn came as refugees from an interplane(tary) war that literally resulted in entire chunks of planets (the "Twelve Planets of Creation") smashing into the surface of Nirn. The ancestry of Men and Mer can be traced to the Ehlnofey, a particular people from a particular place sometimes called "Old Ehlnofey". Some of them showed up on a chunk that landed on Nirn relatively intact: that was Tamriel, and their descendants are what we call the Elves. Others were scattered across Nirn, are known in the Anuad as the "Wandering Ehlnofey" and the ancestors of Men. The only other group that can be traced to this period (and I forget the precise details) were the Hist.
The Anuad then describes a war between the Wanderers, who expected a welcome when they finally found the lands of their brethren, and that era's inhabitants of what we now call Tamriel. There was collateral damage: much of the territory of the Hist was sunk; Black Marsh is all that remains (on this side of the ocean, anyway; there is a theory that the Tscaeci are related to the Hist of Atmora). Dreekius, an Argonian bartender, makes reference to a war that caused the loss of a lot of territory due to their lack of understanding of their neighbors (which Dreekius is a part of the attempt to remedy; his true job is a study of men). I think he may have been referring to the Ehlnofex Wars. My theory is that the Hist created the Argonians from certain tree-dwelling lizards as an "interface" with the descendants of the Ehlnofey.