: Well, I think Martin makes a good point about Aragorn and the Dunlendings. Perhaps some of them accepted Eomer's rule peacefully, but why should they be forced to? Aragorn needed people.

: On the other hand, Gondor's hinterlands were not empty. Tolkien's list of soldiers/volunteers who come to Minas Tirith shows there were people living all over the place. Aragorn could have asked some of them to move north and help rebuild Arnor.

I've had a look at the passage in POME, and yes it says that Eomer took control of essentially the whole of Enedwaith. It is difficult to believe that Tolkien made this assertion whilst remembering the hatred of the Dunlendings for the Rohirrim and the vital interest that the Re-united Kingdom would have in this region which was a land bridge between Gondor and Arnor. Imagine the King of the Dunedain having to ask permission form the King of Rohan every time he needed to move troops or trade caravans through Enedwaith.

Of course the passage does not say in what circumstances Eomer asserted control over this region. As Eomer had forces adjoining the area and Aragorn's nearest settled areas were Pinnath Gelin and later Annuminas (and perhaps Tharbad), it would make sense for Aragorn to make use of his ally's services in the pacification of Enedwaith. Although Rohan itself was an independant polity Eomer may have taken over effective control of Enedwaith as Aragorn's vassal. This is especially likely as the area was not part of Cirion's grant to Eorl, had never formed part of the historic Kingdom of Rohan, and had been in earlier times operated as a sort of condominium between Gondor and Arnor. The institution of the High Kingship may have been revived by Aragorn as an assertion of his wide dominion (Nurn was under his control at least); this political instrument may have been used to regularise his position as overlord of areas beyond the traditional boundaries of Gondor and Arnor and would have made it easier for Eomer to accept a position of vassalage for his new territory, in that as lord of Enedwaith he was not a vassal of merely the King of Gondor or the King of Gondor and Arnor but of the High King of The West.

It is possible that in this extension of his power Eomer may have made exclusive use of the people of Western Rohan who knew the Dunlending language (like Gamling) and had some Dunlending ancestry. In this way he may have lessened the resentment of the Dunlanders to his rule.