Ruled by a monarch, the Emperor, the Empire's exact governmental structure is unclear. The Battle Story portrays an Empire governed by a supreme ruler, whereas the the anime also depicts a ruling council below its head of state.
In the Battle Story, the Empire is rival to the Helic Republic. In the Chaotic Century anime, the Empire is initially presented as an antagonistic invader, but its position becomes more ambiguous as the series progresses.
The exact origins of the Guylos Empire are somewhat unclear. In ZAC 1958, mysterious Zoids from the Dark Continent of Nyx attacked the Central Continent, apparently controlled by Guylos, one of the rulers of the Central Continent. The Zoids were eventually driven off by the forces of the Helic Kingdom. Guylos himself was exiled, travelling across the oceans to Nyx.
At some stage he managed to unify the savage tribes of the Dark Continent into a single Empire. Guylos (or one of his descendants) established an iron-fisted rule over the continent, building a powerful army of savage warriors who had a reputation for fighting until they or their opponents were utterly destroyed. Despite this, many wild tribes remained on the Dark Continent, fighting amongst each other in near-constant battles.
By the ZAC 2030s the Empire was ruled by Emperor Guylos, a descendant of the original ruler of the Empire (although it is possible he may have been the same individual). A dark and enigmatic man, he had a reputation for cruelty, as well as a desire to rule the entire planet.
The Guylos Empire remained largely unknown to the outside world until ZAC 2039. After the defeat of his empire, Zenebas fled to the Dark Continent. Once there, he formed an alliance with Guylos to retake the Zenebas Empire and take over the entire continent. Guylos provided Zenebas with a new army, composed of new Zoids like the Black Rhimos, Warshark and Dimetrodon, as well as creating the massive Deathsaurer.
Zenebas invaded the Central Continent in ZAC 2042, initially steamrolling the Helic forces. However, the Helic Army counterattacked with the Mad Thunder, pushing Zenebas back. In ZAC 2049, as his empire faced defeat, Zenebas made a fateful decision to call for help from Guylos. Zenebas knew that the Guylos Empire would likely destroy the entire continent, but he felt that it would be better to lose everything than let Helic rule it.
The Guylos Army invaded the continent, but rather than attacking the Republic, they instead struck the Zenebas Empire. Zenebas himself was killed and the Guylos Empire took control of its forces. As the Guylos forces attacked the Republic, their effects could be felt across the continent. Plants and animals began to die, the ground became parched and lakes and rivers dried up, as if the continent itself was dying. The source of these events was the 'Dark Zoids' powered by Deochalcum that the Guylos Forces used.
The Helic forces invaded the Dark Continent, only to find themselves in conflict with the strange Zoids of the Guylos Empire. The two forces bogged down in a bloody eighteen-month stalemate in the Devil's Maze, the Helic forces unable to advance past the Guylos defenders. Only the arrival of the Salamander F2, the Republic's new aerial Zoid, was enough to break the stalemate.
Guylos had prepared for this eventuality. He had forced Störmer, the Zenebas Empire's top ace, into his service. Armed with the massive Gilvader, Störmer attacked the Helic air forces and wiped them out. In desperation, the Helic Forces tried to push through with their Mad Thunders; however, the Gilvader descended on them and destroyed them as well.
The Guylos army attacked the Central Continent again, using the Gilvader Force. The Gilvaders wreaked havoc on the Republic, until counter-attacked by a force of Orudios. The lead Gilvader (possibly Störmer's) was speared through the cockpit, and apparently destroyed. Despite this, the Empire continued its attacks, using swarms of the new Gungyarados.
It was only with the arrival of the King Gojulas that the war turned in favour of the Republic. The massive Zoid was able to decimate the Empire's forces, destroying all in its path. The King Gojulas forces advanced towards the capital, with only the Emperor's bodyguards, the Descats, to stop them.
Before that battle could occur, a terrible disaster struck Zi. An asteroid struck one of the three moons of Zi, shattering it and causing debris to rain down on Zi. The meteors devastated the planet; the Central Continent was split into three sections while a portion of the Dark Continent sank into the ocean. Both the Republic and the Guylos Empire suffered severe losses and were unable to wage war; instead they were left struggling to survive.
The Guylos Empire, now confined to the ruined Dark Continent, struggled to rebuild following the devastation. The Empire's population and culture changed as it absorbed the remnants of the Zenebas Empire into it. The Empire became a lot less brutal and savage, ironically becoming more like Zenebas then it originally was.
In ZAC 2097, Guylos died, leaving his ten-year-old grandson, Rudolph, as his only heir. The chief of the armies, Gunther Prozen, was appointed as his regent. In ZAC 2099, Prozen declared war on the Helic Republic, aiming to crush it for once and all. However, due to the presence of Triangle Daras, the so-called Sea of Witchery, a massive impenetrable storm between the two continents, the Guylos Empire could not directly attack the Republic. Instead, they invaded the Western Continent of Europa to use it as a staging ground.
The Guylos forces initially saw great success, crushing the various local forces and the few Helic units deployed there. They managed to seize Mount Olympus, the highest peak on the continent and a vital strategic point. In there, they found the ruins of an ancient yet advanced civilisation, as well as a Deathsaurer. Using the information found here, the Empire was able to develop new Zoids and launch a new offensive.
Despite this, the Republic launched a counter-offensive that forced the Guylos forces back to the Dark Continent. The Republic's army pursued them across the oceans, invading the continent and aiming to capture or eliminate the Emperor. In the midst of the invasion, the Prozen Knights, the elite bodyguard unit of Regent Prozen, launched a coup d'état and seized power in the capital. The Guylos units loyal to Rudolph joined the Helic Republic's invasion forces, and the combined unit attacked the Knights. All three forces were almost completely destroyed when Prozen's Deathsaurer exploded.
In the aftermath, the Eisen Dragoon force, a Guylos unit made up of Zenebas soldiers, took control of the Guylos Empire and renamed it as the Neo-Zenebas Empire. However, elements of the Guylos Empire's government and army survived, fleeing to the Eastern Continent. These forces later allied with the Helic Republic to help defeat Neo-Zenebas.
What happened to the Guylos Empire after that is unclear. Some speculation suggests that they developed a new army based around a lot of the NAR-exlcusive Zoids and variants like the Gravity Zoids, Holotech Zoids and Energy Liger. It is also worth noting that the insignia of the Empire faction from the Neo-Blox line resembles the NJR-era Guylos Logo.
The Guylos Empire initially served as the "antagonist" faction during Zoids: Chaotic Century. The Empire's origins in the series are unclear, but it was likely founded by human colonists who discovered the ruins of the ancient Zoidian civilization. The Empire in the anime is similar to the original version of the Zenebas Empire; the Guylos Empire occupies the western half of the Central Continent, and is far more open then the dark, savage land of the Battle Story.
At some stage, the Republic went to war with the Guylos Empire. This war was rather indecisive, and left a large section of the continent as a vast no man's land of wild gangs, small towns and abandoned military facilities.
Prior to the death of the Emperor Zeppelin, the Empire once again invaded the Republic. Despite initial setbacks, the Empire was able to swiftly advance through the Republic and reach the gates of its capital. A second Imperial force staged an amphibious assault on the capital, surrounding it. Before the Imperial forces could attack, however, Guylos Emperor Rudolph recalled his forces and ended the war.
Despite this, tensions still remained between the two nations. Guylos Regent Gunther Prozen used this as an opportunity to stage a coup, kidnapping Rudolph and framing the Republic in order to restart the war. However, the truth behind Prozen's plot was revealed, the Republic army siding with the Imperial forces loyal to Rudolph. Prozen tried to destroy them with a Deathsaurer, but the combined armies were unable to defeat him. Van and his Blade Liger, however, were able stop the Deathsaurer.
Following the war, the Republic and Empire signed a peace agreement. The two nations formed a joint peacekeeping force known as the Guardian Force. However, the Republic would later come under attack by an Ancient Zoidian known as Hiltz, using a Death Stinger. Hiltz devastated large areas of the Republic, including the capital. He also attempted to destroy the Empire with a resurrected Deathsaurer, but was defeated by the Guardian Force.
The Guylos Empire's earliest know Zoids are the so-called "Dark" Zoids, the Deadborder and Heldigunner. These Zoids used a material known as Deochalcum which allows them to absorb light and heat into their bodies and convert it into power for their weapons systems, making them far more powerful then similar sized Zoids. The ore also gives their powerplants and other systems a distinct green glow, which contrasts to their black armour. The Zenebas Red Horn was also adapted to use this power source, resulting in the Darkhorn.
The Meteor Strike of ZAC 2056 destroyed most of the Deochalcum reserves, preventing the Empire from building more of the Dark Zoids. It also destroyed the technology needed to build a lot of their other Zoids. As a result, the Guylos Empire adapted older Zenebas designs to their use, such as the Red Horn, Iron Kong, Redler and Iguan. They also developed newer Zoids like the Rev Rapter, Geno Saurer/Geno Breaker, Lightning Saix, and Berserk Fury.
Ironically, the Liger Zero, one of the Helic Republic's most notable Zoids, was created from a design stolen from the Guylos Empire. And a new development of the fourth CAS for the Liger Zero is known as the Liger Zero X.