Orcs
Mountain Orcs
"...The breaking into different factions was doing of the Great Shamans. Long ago turmoil reigned in the Lands of the Greenskins; to make things worse, the King was weak and dying. When he eventually passed away chaos broke out with the last of his successors being killed at birth by those laying claim to the crown.
A lot of the Orcs wanted to follow Abugroth the Terrible who was amongst the strongest and most charismatic Orcs that ever lived; his kin respected his strength and wished for him to lead them. The rest decided to remain faithful to their King and royal blood line, protecting it to the death. Inevitably two armies of legendary proportions were formed and ready to clash for dominion.
It would have been a weakening distaster for the Orcs had it not been for the intervention of the wise. To avoid the horrible battle that would have heavily weakened the race of Orcs, the Great Shamans suggested they should ask the council of the Gods. Respecting -and also fearing- the Gods and the Shaman's magic, they agreed.
The Shamans ordered a giant tent to be placed atop the peak of Mountain Oostragoth and closed themselves inside. Mystical smoke and strange invocations could be heard from within but no-one dared enter. The Warlords and chieftains outside were expecting to crown one of them King.
After seven days the Shamans exited and delivered the message of the Gods in an unearthy voice, one not from this world: They were to split in four factions; any faction that dared attack another would have to be countered by the other two or suffer the anger of the Gods. Peace reigned for many years.
Given no faction alone was strong enough to wage war with all three contemporaneously. On the other hand, if any faction needed help, they would sound the drums of war; again, if the others didn't rush to their aid, horrible things would happen to them.
The Orcs obeyed and this stands till present day..."