The Tribe of Fallen Shadows

Origin
The Tribe of Fallen Shadows was created when a ShadowClan adopted mountain cat fought her way to the position of leader. Leaf that falls in running water, Leaf, had always disagreed with the ways of the Clans, even since her mother had brought her there when she was still a kit. As soon as Leaf became leader, she appointed all the other adopted Tribe cats as senior warriors, forced the senior Clan warriors to retire to the elders den by threat of murder, and forced the junior Clan warriors to drop their titles and move to the newly created Slave Den. Leaf named the new tribe The Tribe of Fallen Shadows after ShadowClan's dark territory and after ShadowClan's fall.

Traditional Ways
The ancient Tribe of Rushing Water split the cats' duties into Prey-Hunters and Cave-Guards.

Prey-Hunters would hunt and feed the Tribe and Cave-Guards would protect the Tribe's home and the Prey-Hunters from the talons of swooping eagles.

Leaf's Ways
As soon as all the Clan cats dropped their titles and/or retired, Leaf named the mountain cats Territory-Protecters and the Clan cats, Slaves.

The main purpose of a Territory-Protecter is to battle train and the purpose of a Slave-Cat is to hunt food for the Territory-Protectors.

Slave-Cat rules:
The Slave-Cats are "temporary" meaning that they will serve the Tribe as long as they can until they starve to death. Leaf wanted her Tribe to be of pure blood and to have no Clan cats of the sort.
 * Must hunt for the Territory-Protectors when ordered to
 * Must share one piece of prey between themselves as dusk
 * If not hunting, must stay in the Slave den

Territory-Protector rules:

 * Must train for battle all day
 * Must patrol borders when ordered
 * Expand territory where possible
 * Threaten any other cat that isn't part of the Tribe

Leaf's Purpose
Leaf hoped that by destroying ShadowClan, the other Clans would fear her. She was battle training her cats to be the strongest at the Sunpath and was hoping to take RiverClan hostage soon. However, an equally cruel leader had destroyed PoolClan, around the same time she took ShadowClan, creating BoneClan. BoneClan was equally as strong and hoped to destroy ThunderClan and grow as well. StarClan predicted that BoneClan and the Tribe of Fallen Shadows would start a war that would wipe out the Clans forever.