The northern frontier were not particularly warlike, but because of their need for food and basic living resources they had to trade with the two staes of the western coalition. Now because of their military might, their trade deals were quite agressive and could be considered unfair. Demanding ridiculously cheap prices for what they wanted and offering elementus at an insanely high price. Now the proud Hylo Empire saw this as economical warfare as the northen frontier was essentially dictating the market. The Hylo Empire was also the first reigon to utilise the solar panel farms as their main source of energy which was actually far cheaper and easier than trading elementus or buiding nuclear power plants. So they began to push back against the unreasonable prices with the frontier which created some tension but they eventually gained some leverage on the market.

The Therux state were somewhat more paranoid of the froniter stockpiling large mecha armies, and after seeing the pushback of the Hylor Empire, they called for an end to their rivalrly and proposed a coalition to stand up to the northern frontier if they ever tried to attack. Unfortunately this coalition and build up of a huge joint army made the northern frontier very nervous and while trade continued both reigons were ready for war. The military conflict was sparked over a small skirmish between Frontier and Hylo Mechas in the fortune reigon over the builiding of a tower. The Hylo forces claim it was a defense garrison that the frontier were trying to expand military structures in the land, but the frontier claimed it was simply a generator building to refuel scout mechas in the largely undiscovered territories. No one can confirm truly what the building was but due its ability to start the world's biggest war, it has been called Tower of Helen.

The Hylo forces destoryed the Helen tower and the frontier forces fought back in a small skirmish with zero casualties, but the act of agression was enough to send the fully paranoid northern frontier into full scale war with the Hylo Empire which now was backed by the Therux state. The war was largely the frontier sending invading forces to the western lands and being beaten back. While the strategic nightmare of attacking the northern reigon made any offense for the Western Coalition nigh but impossible. No territory was lost, only soliders, civilisations and mechas. But the war went on for so long that it turned the world into what it is today, an economically damaged dystopia, with crippled armies on each side constanty in fear of another war.

Mk 1
Mechs based on fuel, these are largely obsolete in modern combat and havent seen much use since the Western Wars of around 45 years ago. However they are incredibly cheap to make and many low level security mechs run on feul, they are usually slower and and prone to over hearting and combustion as well as burning through fuel fairly quickly in high impact confrontations. One mecha type that is still used is the Mobile Armor style dreadnaught class. Huge expensive tank like machines that can only run on fuel (largely due to costs) that are rarely seen but very difficult to take down. Mk1 Example

Mk 2
These make up 80% of mechs in use, the standard of modern conflict. These Mechs run on generators, which can vary from Fusion cores to Solar powered to electricity or a combination. They come with none of the shortfalls of Mk1 mechs an enjoy almost unlimited activity with no worry of overheating or meltdown (although there are fringe cases) the life battery of generator is self sustaining and as long as it is maintaned can fuel a mech for years before needing to be replaced. Also because of the amount of power generated Mk2s can employ heavier armor with lighter engines that fuel based mechs would not be able to support.

The pinnacle of the Mk2s are those that are equipped with the aformentioned 'Hybrid Generators' as these are the most expensive but generate the most power. The Mk2s are what the players will be using and are generally known as Mk2+ and represent the fighting elite pilots in the western world.
Mk2 Example

Mk 3
Finally the mecha that run on pure elementum are the pinnicle of modern mech design, everything a Mk2 can do the Mk3 can do better, raw elementum generates almost 5 times as much power as hybrid generator, and the amount of speed that can be generated from an elementum engine is blistering. Elementum is nigh indestructable so there is no danger of overheating or failiure and the life span of an elementum fueled engine has so far proven to be infinite. Also the engines are so powerful that they can be made super compact for even lighter weight and sharper performance. The only real limiter is the cost it makes to make a raw elementum engine so these machines are ridiculously expensive. Usually only afforded to the very top class operatives of the northern frontier.
Mk3 Example