Enemies of Gondor

Easterlings are men who refused to make contact with the elves during the great western migration during the early second age. They were cruel perople, but proud. They benefited with their alliance with Mordor. They gave Sauron disciplined warriors and in return he gave them the land they had wanted for a long time.
The Haradrim. They had been ruled mercilessly by the Numenoreans and wanted revenge. There lands were barren and they wanted Gondor's fertile plains.
The Corsairs. These guys used to be part of Gondors navy and were rebels. They were driven south. They would raid the coastline south of gondor. They wanted treasure.