Cold War was a deadly 1000 years battle between a Sye'lla Massive Spatial Army and Coldian Warriors.Coldian Warriors are normal humans that declared the Cold War to Sye'lla System,and they called themselfs a Coldian Warriors because of a Cold War.Coldian Warriors had their own leader that they called Coldian Commander.Coldian Army had their weapons,vehicles and evrything that was needed for war.
Planets like:Shadow Moon,Corrisa'ika (planet),Yankorn IV, D'Vedr (planet) and many others were invaded by Coldian Warriors.Corrisa'ika Imperial Republic,D'Vedr Roayl Monarchy was doomed.Only Yankorn Government and Shadow Moon Survived the invasions.Coldian Army was flying around the Sye'lla system for 1000 years, they were searching for new planets to attack. More than 1,000,000,000 people was found dead during the invasion of Coldian Warriors.
No one actually can say where Coldian Warriors came from.They've somehow located Sye'lla system and wanted to take it over.Someone says that they came from other galaxies.Someone says that Coldians are people from Sye'lla System that came up with same idea to attack the system,there are a lot of versions but the truth is unknown. Coldian Warriors were forced to leave in the end of First Era,but in the end of Fourth Era small group of them returned and attacked Yankorn IV.