Maybe the Variags were in the movies after all?

While it's true that Jackson had limited descriptions to work with in the novels, he did make some creative decisions regarding the representation of various peoples and cultures in Middle-earth.

In the films, the Haradrim are depicted as a significant force fighting for Sauron, especially in the Battle of the Pelennor Fields in "The Return of the King." It's possible that elements of Khandish culture or imagery were incorporated into the portrayal of the Haradrim, given their proximity to each other in Middle-earth.

[William Cloud Hicklin]

Harad simply means "South," and clearly the Gondorians used it as a catch-all term for all the many peoples who lived south of the Poros, from their own kin, Black Numenoreans (and later Gondorian rebels) in Umbar, to the "black men" out of Far Harad.

PJ at least attempted to show this diversity, given the very different appearance and dress of (a) the Southrons encountered at the Black Gate by FS&G, (b) the very different, somewhat "Persian" Southrons ambushed by Faramir's Rangers, and (c) the entirely different vaguely "Polynesian" Swertings driving the Mumakil at the Pelennor.