In ZAC 1000, the first humans arrived on Zi, finding a native race (commonly referred to as Zoidians) that looked exactly like humans in every way. This race had partial psychic abilities that allowed them to "talk" with the native animals that live on Zi. The animals in question where the Zoids, a race of mechanical being that resembled both mammals and dinosaurs ( Dinosaur styled Zoids are more commonly associated the Zenebas and Gylos empires, while mammalian Zoids tend to be associated with the Helic Republic).
The humans had traveled to Zi because of the declining health of the mother-world, Earth. They traveled in huge "colony ships" named Globally 1,2,3,4,6,7 and 10. Note that 5,8 and 9 are missing. There is no knowledge of what happened to them, but it is believed they where lost in space along the journey from earth. Each ship left Earth one day apart, but ended up arriving between 200-500 years apart. Only the Globally 3 arrival is significant in the battle story.
The original human government is unknown, but in ZAC 1500-1800, the Helionic kingdom (later the Helic republic) was established on the central continent. At this time, the Zoidians had begun interbreeding with humans and true Zoidians were in rapid decline. The Zoidian government, seeing the potential for war in humans, hid their technology and placed the Zoid Eve in a tomb below the Valley of the Rare Hertz.
In ZAC 1955, the Helionic king, King Helic, unifies all of the smaller tribes of humans on the central continent. He renames the Helionic Kingdom the Helic Republic, and rules as president. When Helic dies, His eldest son, Helic The Second (Helic II) is elected President while his younger brother (Zenebas Muroa) is placed in charge of the military. He constantly argued with his brother and the council, believing their peace loving ways to be a waste of time, and was eventually exiled to Europa, where he formed his own empire.This was followed by a 47 month war between the Zenebas empire and the helic republic. This point in history also marks the beginning of the original battle story. This war was known as the Helic Heresy, due to the fact that the Zenebas empire was founded by King Helics own son. The main Zoids employed in this war where the Garius, Gator, Geruder, Aquadon, and Elephantus. The end of the war came when the ship from earth, the Globally 3 crashed into the western continent, where the fighting was taking place. Both powers absorbed the refugees into their ranks, and used the advanced earth technology to develop better weapons. This would lead to an arms race ending in the Death Saurer.
In Zac 2028, the fighting started up again. Both sided had better Zoids and weapons thanks to the earth technology. This new conflict was known as the Devils War, because both sides constantly employed more powerful Zoids.In the 11th year of conflict, in ZAC 2039, the Ultrasaurus was deployed by the republic. The fourteen Ultrasaurus produced were piloted and maintained by the 6th division, an elite group of pilots and mechanics from a mixture of the 3rd and 1st divisions. The 6th division was dubbed the "Morning Stars" due to the sheer power of their Zoids. The Ultrasaurus were able to turn the tide of war against the Zenebas empire, forcing them to flee to the continent of Nyx.
In 2045, a small task force of Zenebas Gurrila Warriors piloting Zaber Fangs attacked the 6th division, badly damaging but not destroying two Ultrasaurus. This was the debut of the beam canon, originally used on earth for mining. The Zenebas empire was able to reconstruct the beam cannon from the damaged remains of the Globally 3, which were transported back to Europa when the Zenebas empire had an advantage in the war. Although the beam canon proved extremely useful (later becoming a standard imperial weapon), they failed to turn the tide of war. Zenebas himself then sent a large army to attack the eastern shores of the central continent, which were the weakest part of the republic. The small guerrilla force continued to attack specific targets until it was destroyed in ZAC 2052. The meteor shower of ZAC 2056 brought this era to an end.