From Thains Book (tuckborough.net):
2280
The Numenoreans build a great fortress at the Havens of Umbar.
3261
Ar-Pharazon lands at Umbar with a great fleet and takes Sauron to Numenor the next year. In the years following, the Haradrim are enslaved and sacrificed by the Numenoreans.
3319
Destruction of Numenor.
3320
Foundation of Gondor. Sauron returns to Mordor.
3434-3441
Haradrim fight for Sauron in the War of the Last Alliance. Sauron is defeated, the One Ring is taken from him, and his spirit flees Mordor.
Third Age:
933
King Earnil I of Gondor captures Umbar.
936
Earnil is lost at Sea off the coast of Harad.
1015
The Haradrim try unsuccessfully to retake Umbar. King Ciryandil of Gondor is killed. The Haradrim besiege Umbar for the next 35 years.
From what I see, Umbar was under Numenorean control at the end of the Second Age. I would agree with Zimoo with their minifactions, it would make them much more unique.
Edit: but also says:
Ar-Pharazon of Numenor landed at Umbar in 3261 with a great fleet and the people on the coasts fled before them. Sauron's forces refused to fight, and he allowed himself to be taken to Numenor where he corrupted the King and his followers. Under Ar-Pharazon, the Numenoreans made war on the Men of Middle-earth, and they also enslaved them and used them for human sacrifices. Men of the south long remembered the actions of the Numenoreans in their lands.
The Numenoreans who lived in Harad survived the destruction of Numenor in 3319. They became known as the Black Numenoreans because they remained under the influence of Sauron. Two Black Numenoreans named Herumor and Fuinur rose to power among the Haradrim. Many Black Numenoreans lived in Umbar, while others lived farther south. Over time, the Black Numenoreans dwindled and their bloodline became merged with the Haradrim.
Edited by mh_gollum, 22 May 2007 - 07:21 PM.