Nope, we went to Solstheim. Which is actually in the province of Morrowind.
Technically, during the time-period MW was in, it was a sovereign state, aka owned by no other province. After Infernal City, though, that all changed. (I don't really know what i went to)
I would still love to see the Argonian homeworld! That would be something! Imagine the creatures you would find there.
Argonia/Black Marsh would be one of the most dangerous places in Tamriel. It's so dangerous that no men live there because of some kind of disease/plague that routinely wipes out almost all men that try to live there. And that's not to mention the humongous creatures the size of houses/buses.