The Final War was an Ancient war which inadvertently destroyed their civilization as well as the splitting of continents.
Chronology[]
Before the Final War[]
Before the Final War had started, the Ancients (humans) had reached a supreme technological state which was so advanced that the Ancients could create life itself and later store the genetic information of any organism into CD-ROMs. They became so technologically superior that they strongly believed that they were gods. According to events of Monster Rancher 4, this belief was reinforced by the discovery of limitless potential within monsters through the teamwork between Suzaku the Phoenix lord and princess in stopping the dreaded dark lord Xevion which culminated to them sealing him within a disc. Seeing his error in bringing humans into the monsters' quarrel, Suzaku, whom foreseeing the oncoming conflict started by both this discovery and further advancements of the Ancients, approached the king about his daughter's safety. Together, they agreed and Suzaku sealed the princess inside a Mystery Disc and hid it away to keep her safe. This disc was found hundreds of years later by a young Shrine master named Cesare who unlocked it and raised the girl as his daughter, Rio.
The conflict that Suzaku feared, The Final War, eventually came to pass where the tension between humanity escalated to devastating level when natural disasters plagued the every corner of the world, deprived them from their resources and shelters in spite of their vast technological advancements.
The Final War Erupts[]
With the natural disaster worsen their conflicts and their desperation to survive, the Ancients fought against each other in order to get what they need, and that's how their conflicts turned into the Final War. It was then the Ancients had lost their good will and were forced back to where they had to fight to survive.
The Final War lasted for so long that Monol, who tells the The Searchers about the war, only able to hinted that the conflict lasted for more than centuries. The rapid losses over the course of the conflicts prompted the Ancients to modify and bio-engineered monsters as well as creating brand new monsters altogether for war where Melcarba being one of new monster breed developed for war. However, each forces had the same idea and in the end, the War was mostly fought between the monsters whilst the humans were protected.
It was then the true reason to the escalation of the war was forgotten about and only the hatred was passed down, not the knowledge as to why they are fighting.
Pendant built an underground city for its experiments in an attempt to create the ultimate, unbeatable warrior as they were confident that this could end the war successfully. It's unknown in how long it took, but the scientists ended up creating Moo, who was successful in fighting away the enemies. But then, Moo turned against its masters and eventually became Master Moo; possibly for the belief that it was powerful and it shouldn't be ordered around. It vanquished everything in sight and began to turn monsters into Baddies by amplifying the darkness within their hearts. By this point, Master Moo is no longer any sides' weapon anymore, but a Dark Lord that succeeded Xevion in the past as much as being incarnation of sentient beings' hatred within the husk of a heavily modified Dragon.
And so, in-order to survive, the remaining Pendant scientists escaped from a now-ruined city and would later unite under one banner for ex-enemies to find a way to destroy Master Moo. The scientists found a way and so decided to fight fire with fire: They begged for Suzaku's help and the Phoenix lord agreed. Suzaku allowed them to modify him for battle, resulting the Phoenix lord's powers drastically increased: His ability to exorcize Baddies back into their original good selves was amplified that he can potentially purify the entire planet of Baddies. In spite of his valiant efforts against an advesary whom poses similar threat with Xevion's, Suzaku and Moo's powers were proven to be equal, as they were unable to defeat each other.
It was then the surviving Ancients chose to create a weapon of last resort which would render Moo harmless as well as means to aid the Phoenix lord, which was coined the Final Gate. Despite warnings the device could harm all the monsters includes Suzaku, the Ancients had no choice and so activated the weapon, with Suzaku voluntarily became it's beacon. When the Final Gate constructed, Suzaku buy them some time by keep Master Moo at bay, long enough for the scientists to separate Moo's mind from his body by activating the weapon.
Unfortunately, that meant that the same happened to Suzaku, and because he was the beacon, his soul recieved the most damage, being split into five pieces. It was believed that the five pieces of the Phoenix's soul fell from the sky and embedded themselves in five mystery discs, which later were revealed as Mocchi (the Phoenix's courage), Suezo (Phoenix's pride), Golem (Phoenix's kindness), Tiger (the Phoenix's anger), and Hare (Phoenix's intelligence).
Not long after Suzaku's sacrifice to stopped Moo, the weapon predictably suffer malfunctions, but the Ancients were unaware of what its effects and as it radiated a different type of energy, all the Monsters, includes Baddies, were forced back into their mystery discs, whilst the continents would split apart and volcanoes erupt. The Final War was over, as well as the Ancient Civilization which was highly advanced was now a primal scattered society where humans would have to rebuild that what they torn down, but became highly aware of the Final War and its effects afterwards and the infamous Final Gate and the Moo and the Phoenix, but did not have the knowledge of technology and so became primal and unable to restore to their former glory.
"Their advancements in civilized conveniences were soon forgotten. The thin veneer of civilization was stripped away and the people became savage." -Monol