There is some debate as to how many categories are necessary in order to describe the troll race. Several notable authorities on the topic have chosen to specify a fifth category: namely, the dark trolls.
Historical capital: Zul'Farrak
Known tribe: Sandfury
Description: The sand trolls' skin is coarse and cracked, and its color tends to be brown or gold. Sand trolls also have thinner manes of hair than their brethren. Sand trolls mostly keep to themselves and attack all outsiders.
History: The chaos of the Great Sundering isolated one of the tribes that had been living in the fringes of the Gurubashi empire. The relentless desert sun of Tanaris beat down on the trolls, who gradually adapted to their harsh new environment.
The sand trolls have never formed an empire. In fact, they have gradually been forced to surrender much of their lands in Tanaris, though they are defending their current territory with great tenacity.