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.
Marvel UK Comics
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.
Two of the gladiators, Megatron and Optimus Prime, and the Overlord and his two bodyguards attempted to escape the war by traveling to Iacon. The group were slowed to a halt just at the border by the Overlord's energy depletion and Optimus Prime rushed ahead to get help from Iacon. While they waited one of the Overlord's bodyguards, Nightstalker was killed. Megatron and the other bodyguard, Ravage, then abandoned the Overlord to die, making their own way to Iacon.
After Tarn and Vos had destroyed each other with photon missiles, Megatron recruited many of the survivors into his new Decepticon army by laying blame on Iacon.
