Rhun cannot be reached by ship as yet. Even if the ME used is the "round from the beginning" version, no vessel would sttempt to sail.aound all of Harad to come to Rhun from the South. They would not know that this is even possibile, they would not know the way and they would starve and die of thirst several timex over in an sttempt like this.This may have been dissatisfying in the S1 story (not having information about these random Southlanders), but I don’t see this as a problem transitioning into S2 - just some gaps that need filling at some point. We know there are civilisations beyond the maps because of the inclusion of Rhun as a place.
So the whole setup for humans in ME is lacking. And what is Haradrim hunter up to in Dagorland?