In the beginning, there was Azeroth. It existed as one continent called Kalimdor. Prior to the Sundering -- indeed, prior to the rise of the elven race at all -- there were the trolls. The troll race is one of the first sentient races on Azeroth, it's been suggested on more than one occasion that the troll race predates even the arrival of the Titans. Needless to say, Azeroth is full of trolls, from the Darkspear, Horde allies that joined during the orcs' trek to Kalimdor from the Eastern Kingdoms, to the various splinter tribes scattered across Azeroth.
But the troll races share a common point of interest -- once, long, long ago, these trolls were all part of one empire, one tribe of trolls from which all others originated. The Zandalari tribe isn't an unfamiliar name to those that have played through Northrend content. The Zandalari were assisting both Alliance and Horde against the maddened remnants of the Drakari ice trolls. However, players were first introduced to the Zandalari in vanilla, when the mysterious progenitors of the troll race appeared to ask for help from both Alliance and Horde against the combined might of the Atal'ai trolls to conquer Zul'Gurub -- once the capital of the Gurubashi Empire.
Please note: This edition of Know Your Lore spoils some elements of the upcoming 4.1 patch, Rise of the Zandalari. If you'd like to avoid spoilers for upcoming content, turn away now, before it's too late!