Kossith is the racial term for the horned humanoids that make up the Qunari. Qunari are not a race, but the followers of the Religion known as the Qun. The majority who follow it is made up of the Kossith, that is, the giant horned humanoids. There was an offshoot of kossith (possibly unaffiliated with the Qun, no records to indicate otherwise) that settled into the Kocari Wilds before they were attacked by Darkspawn. Khan's character implies that there were a few survivors, who possibly mingled with local human populace and thus, how her character is partially Kossith.