Tribes Extreme introduced a new tribe, the Grievers, originally dispossessed scavengers who picked over battlefields and mourned the dead in the aftermath of the Cybrid Wars, the so-called "grievers" have evolved into loose clans of pirates and smugglers by the 40th century. Some griever bands are mere traders and scavengers, the gypsies of the wilderzone who are a common sight in fraytown bazaars and auctions. Others – called peshtûl by the “true Grievers” — are composed of tribal outcasts and murderers who turn to outright piracy.
Imperials claim they cannot tell the difference between piratical Grievers and tribal raiders. The Tribes of Man know the distinction is simple: Grievers have no honor. They raid and kill indiscriminately, like maddened beasts. The Tenets of Harabec do not apply to Grievers. Nevertheless, those tribals who treat Grievers well may win themselves valuable and useful allies, for the Grievers have contacts across the wilderzone and accumulate much gossip and interesting data.
The Tribes Extreme campaign opened with the "Bone Ripper" tribe of Grievers having completely wiped out the player's holdfast (a military/civilian homestead where tribesmembers live), killing almost everyone. In the Greater Tribes, this is completely taboo - battle is highly structured, even ceremonial - you never attack civilians. The player must first rid his holdfast and surrounding area of remaining Bone Rippers then seek revenge.
With the cancellation of Tribes Extreme, this tribe never officially enters the Tribes universe and its timeline.