Stonetalon centaur

The Stonetalon centaur were a group of centaur that made their home within the Stonetalon Mountains. Their Khan had a Glyph of Purification within his possession that Thrall would need to cure a befouled fountain during the Third War. As such, the centaur came under attack by the Horde which not only claimed the glyph (allowing the Horde to use the fountain to heal its warriors), but seemingly also destroyed the group.

Speculation

 * Since they were led by a khan, they were likely a tribe or a clan.
 * They could be a small faction of one of the five main centaur clans, or a group that splintered from them.