What happened to Mordor?

[Tuor in Gondolin]

Originally Posted by zxcvbn
No, Gondor wasn't a colonial power.

Actually, Gondor, and later the Rohirrim, were essentially
colonial powers in Rohan, chasing out the Dunlendings-
which is why that folk helped Saruman.

From Robert Foster's the cpmplete guide to Middle-Earth:

In the Third Age they hated the Rohirrim, who
had driven them out of the northern valleys of the Ered
Nimrais and the plains of western Rohan, and so they
frequently attacked that country.

I must say I've always been not unsympathetic to the
Dunlendings plight, reminiscent of North American and
Australian native peoples (but without the virtual genocide
conducted in those regions).