Tarn (polity)
Tarn was one of Cybertron's many city-states before the advent of the Great War and was ruled by a military dictator named Shockwave.
War had broken out between Tarn and Vos despite an Overlord's attempts to lay the foundation of peace between Cybertron's city states by holding the State Games, which were arena tournaments. One of the combatants, Megatron, had agreed to escort the Overlord to Iacon in the middle of the conflict between Tarn and Vos, but Megatron only took him so far before simply watching him die from energon depletion.
After Tarn and Vos had destroyed each other, Megatron recruited many of the survivors into his new Decepticon army by laying blame on Iacon.
Though this is speculation, one cannot help but wonder whether this war was engineered by Megatron, considering that the leaders of Vos and Tarn were both high ranking Decepticons under his command. It was not clearly established whether Shockwave and Starscream were already part of his movement, or joined Megatron during his recruitment campaign in the aftermath of this conflict.
