What World of Warcraft expansion do you get taurens as a new race

Taurens are part of the original World of Warcraft races.

Original Races: Tauren, Human, Orc, Troll, Gnome, Night Elf, Undead (Forsaken), Dwarves.

Burning Crusade: Blood Elves and Dranei

Wrath of the Lich King: No New Races, but the Death Knight class was introduced.

Cataclysm: Will have Goblins (Horde) and Worgen (Alliance).