A people of Rhûn who in the days of Cirion, Steward of Gondor, (c.2489) migrated en masse to lands formerly occupied by the Northmen of Rhovanion. From here they staged frequent raids into the lower Vale of Anduin (probably at the instigation of Sauron who at that time dwelt in DolGuldur), emptying that land and driving its folk into the north.
In 2509, Cirion became aware that great numbers of the Balchoth were massing along the southern borders of Mirkwood; he sent a team of messengers on a perilous journey north through Balchoth- and orc-infested lands to the Éothéod, who dwelt near the sources of Anduin. Thus it was that in 2510, when the Balchoth finally invaded Calenardhon, Eorl led a host of his people south to the aid of Gondor, arriving in the nick of time at the Field of Celebrant. The Balchoth and orc armies were swept away, and the Éothéod were granted the underpopulated region of Calenardhon. The Balchoth disappeared from the histories of Middle-earth after this time.