Basic Information from Blizzard regarding Trolls:
The vicious Jungle Trolls, who populate the numerous islands of the South Seas, are renowned for their cruelty and dark mysticism. Barbarous and superstitious, the wily Trolls carry a seething hatred for all other races.
One tribe, however, was forced to overcome its prejudices when it encountered the Orc Warchief, Thrall, and his mighty Horde. The Trolls of the Darkspear tribe, long since exiled from their ancestral lands in Stranglethorn Vale, were nearly destroyed by a band of aquatic Murlocs, but Thrall and the Horde managed to save them. In return the grateful Trolls swore an oath of eternal allegiance to the Horde.
Lead by the cunning Shadow Hunter, Vol'jin, the Darkspear Trolls now make their home in Durotar along with their Orcish allies. Their village, named after their fallen tribal elder, Sen'jin, lies along the eastern coast of the harsh, rocky land. The Darkspear tribe also occupies tracks within the nearby jungles of the Echo Isles.
As part of the Horde, the Trolls have extended their loyalty to the mighty Tauren, but they have little trust for the manipulative Forsaken, whom they believe will visit only misery and strife upon their allies.
Start Location: Durotar
Home City: Orgrimmar
The TenTonHammer take on Trolls
While they may look thin and frail compared to their orcish counterparts, the Trolls of the horde offer another interesting race that can be played. Starting in Durotar along with their orchish counterparts, the Troll race can easily be paired with other orcs when players want to do new character groups.
Eventually Trolls may wish to make the sojourn back to their ancestral homeland in Stranglethorn Vale. The original domicile of the Trolls can be found due south of Duskwood and is meant for a mid-level party to explore.