Crossing the Plains of Rhovanion
Information about the East is sparser and sparser the farther you go, but there have been rumors of the Drift... according to some rumors, it's called the Drift because the hills... drift. They move. Slowly, but not in a straight line. Across the 200 miles or so, new hills slowly form to the north and drift south until they disappear.
Then there's the tale of the Dark Towers--two of them. This is an even more nebulous rumor, but probably more made-up than factual. Since the hills drift and disappear, any towers on them would vanish, too, wouldn't they? So to get around that 'contradiction', the towers also move, which is why they are also known as the Towers That Walk.
It also said that Men of Darkness live in them, but that may only be an association based on words.
As near as anyone can tell, these 'tales' come from Wainriders of Rhun, who may, in turn, have gotten them from trading with the Men of Darkness.