The Belgariad
Marags are the people of Mara. They are generally thought to be extinct at the time of The Belgariad, after a genocidal war waged by the Tolnedrans. It is later revealed that Tolnedrans sold Marag survivors to Nyissan slavers who in turn sold them to the Murgos, and that some still lived in the slave pens under Rak Cthol.