Underdar

The Underdar culture is not only the partial origin of the name of the Underdark, but is the ancient culture of it from way before our time. This culture, born as the main culture of the Orcs of the Underdark of Dwarovar was the most warrior-like culture of our history.
In the Underdar culture the main way to rise in rank was to take your rank by force - as you took the rank of whoever you killed. Whenever a move in position like this happened, it left behind an empty position from where the claimant rose, revealing the second way to rise in rank: survive long enough to slowly move up the ranks.
Even children frequently took part in duels, although duels to the death were later only permitted for adults - a move some consider the beginning of the fall of the Underdar culture and move towards a more Underdali approach. The culture itself started dying once Elves replaced the Alelf Society and started partaking in the culture not by strength, but by cunning.
Frequent disagreements rose on whether a kill "counted" or not, and this quest on invalidating the Elf ways has resulted in their divergence of cultures. With the divergence of cultures came tribes and factions, and with those came war. The Orcs could no longer afford to rapidly kill each other as now they had an enemy for the first time. Ironically this made them also adapt towards the Underdali ways.
Many of its ways and teachings still exist in the Underdali culture of today.

Diverged ethnicities

• Underdali