The Tribal expansion includes the four Tribes of Eurasia found in the Mutant Chronicles Universe especially as outlined in the Dark Eden book. Two heroes from each tribe make an appearance and are playable as long-term characters for the Mutant Chronicles: Siege of the Citadel game. The tribes include the Rasputins, Crescentians, Inheritors, and the Templars.
- Sons of Rasputin - Von Berg (Fire Combat Specialist) & Von Strasser (Close Combat Specialist). Nobles with access to greater funding, Rasputins begin with one additional Credit.
- Crescentians - Prophet Nandor (Close Combat Specialist) & Khan (Fire Combat Specialist). Crescentians can foresee the future. They may look at the next Event card one round before it is drawn.
- Inheritors of Job - Nemon (Close Combat Specialist) & Cathal (Fire Combat Specialist). Inheritors are so strongly linked they may freely share wounds between them.
- Templars - Verage (Close Combat Specialist) & Labid (Fire Combat Specialist). Templars are vicious fighters, each receiving 1 extra Close Combat attack action for the round.
The Tribes of Eurasia may be used with the Siege of the Citadel or Cathedral campaigns. The Tribes may be selected as the player's team for the campaign as in Siege of the Citadel through random draw of the Tribe's turn marker before the first mission. Tribes loose promotion points in the same way as the Corporations when attacking another Tribe or Corporation. Dark Legion may freely attack the Tribes with no penalty and vice versa.
- Sons of Rasputin - When a game begins, the Sons of Rasputin start with 1 additional Credit more than the other players. This enables them to begin ahead of the other forces by obtaining weaponry not yet available. If this is used wisely, the Rasputins may maintain a lead through an entire campaign. Sons of Rasputin do not gain an additional Credit per mission.
- Crescentians - Well versed in forsight, Crescentians are able to pick up the next event card after the last one has been played or, at the beginning of the mission, at any time before it is played. They may not share their insight with other players (table talk). The Crescentian power enables them to prepare for the next onslaught of reinforcements, or position themselves where need be should the mission or layout change.
- Inheritors of Job - Strongly linked to the point of expereincing one another's pain, Inheritors may share wounds or health freely between them. Medical injectors and the like provide regeneration to one, the other, or both in part up to the health restored.
- Templars - Ruthless in combat, these Doomtroopers do not hesitate in battle. Each figure receives 1 extra Close Combat action for each round of their activation. If the action cannot be used, it is lost, not cumulating through a mission. The 4 maximum actions per turn, per figure rule still applies.