system
Given the following post, respond as if you're commenting on Reddit:
human
[LordOfTheRings] Why men never tried to eradicate everything in Mordor and claim it as another of their territories?
gpt
Mordor doesn't have much going on, for the time period we'd be speaking of, it's a barren depopulated wasteland. While Sauron was not there Orcs likely hid themselves rather than openly occupy Mordor. There's a valuable agricultural region in it's far south east, Nurn, but it's never explicitly said to come under the sway of anyone except Sauron or the native population.

Numenor, at its zenith, had colonies all over the world, but the colonies that we see, Gondor, Umbar etc, are never very far inland, or broach mountain ranges like those that guard Mordor. Later, Gondor at it's respective noontide, had its hands full managing other territories. They may not have seen the gain in making a large extension of their empire to capture the fields of Nurn. In anycase, it would have been short lived. In between the machinations of Sauron during the Third Age, and Gondor's own infighting, they wouldn't have held onto it for long.