This isn't the full history of the setting, but it is a decent summary.
The two planets, Terra and Draco, both awakened from the Zero Age with a few peculiarities. Terra, a well-developed planet with a population of millions, found that its entire population had been sleepwalking, sleepeating... without explanation, they had walked through their daily lives for an unknowable period of time. Part of their planet's history seemed to be missing in every form--book, electronic, and biological memory. With little choice, virtually all of them went back to their daily life, trusting that it would all make sense someday.
Draco, a developing planet with far less history, marked the end of the Zero Age by coming out of an age of civil war. Of principle interest, towards the end of that civil war, a mysterious figure had traversed the world, building temples that repelled anyone too feral to think for themselves. As the buildings were completed, people began to be born with mystic powers, powers divided up into seven elements. These powers, they began to understand, were bound to powerful spiritual creatures that dwelled in the temples, which they called Dragons. Awed by the powers they were awakening to, they split their entire continent into seven enormous nations, one temple apiece, and swore off total war forever, for fear of ruining the land itself. They did not, however, swear off combat, and indeed warriors continued to struggle and fight, both in small measure and in clashes between nations.
In this way, Draco continued through their First Age, learning about and expanding upon the Dragon System. Nations began to create their own Dragons, sometimes for good, sometimes to create powerful warriors. The Yunian Society of Masters arose, as did the Void Followers, and many other factions. The personalities of the nations stabilized, and their borders never wavered more than a few dozen miles. The Great Earth Temple was constructed in Daeyul, a giant stone building that stretched to the skies, containing a wealth of mystic and mundane knowledge that would never be rivaled.
Terra, however, had a far different life in its first act. In the First Age, holography began to take off as a means of direct energy manipulation. At first, it was only industrial--creating static, solid structures and machines out of energy that were dangerous and hard to control. But with the first test of holographic weaponry, the entire world was stricken with fear. Not for nothing did it come to be known as "Post-Nuclear" weaponry; they were weapons without limit, capable of breaking the world apart. Legislation was suggested and widely passed, worldwide, to prevent amateurs from dabbling. But with the internet already in place, it was impossible to contain it, and enthusiasts the world over were simply driven into hiding, not defeated.
On this stage, a man received a strange package of information, one that contained a few necessary ideas and equations. Those ideas and equations, along with a few happy accidents, gave him access to holography in ways that had been impossible--including self-sustaining holographic computers, complete with tiny, fusion-based power supplies. Disgruntled by the worldwide panic and their willingness to persecute scientists for their curiosity, he used his power to remake himself into a nearly superhero-esque figure under the alias Domino Effect. He built a giant, flying city on a flying plate of black iron, and dubbed it Black Hat City; it was his sanctuary for all scientists and engineers, his Mecca in the sky.
His claim to infamy, however, was that he scattered coins across the world, coins made of holography. Anyone who picked one up was granted a wish; they may create any single piece of holographic equipment, including ones that gave them their own, limited superhero (or -villain)-like abilities. The coins were distributed absolutely at random, no matter to whom or where on the planet, so that (from his idealistic view) the governments of the world would never again be allowed to ignore the needs of the poor or homeless, or social minorities or wage-slaves, or any other caste whose life had been hell because of uneven distribution of power.
It worked, in a way. After several decades of horrible, bloody civil wars worldwide, most of the world had access to at least food, power, network access, and medicine. Law, however, was strict and draconian; despotic rule had returned, because military might was the only way to keep the world in order. Still, somehow, Domino kept distributing the coins, dubbed Pandora Keys, and--to his own credit--defending cities and innocents from people who would abuse them, wherever he could. And nobody seemed to be able to replicate his abilities; even with the coins in-hand, they lacked the few central concepts necessary to reverse-engineer them.
In the middle of all this, a long-forgotten project resurfaced. The HELIDER project, once believed to be a failed attempt at a power source, had since a while back been understood to be a portal generator. However, their first prototype vanished--along with everything in a mile-wide sphere. As they were conducting studies on its nature as a portal, they began to get anomalous readings, ones indicating the original prototype had re-activated--half a galaxy away. This, understandably, piqued the interest of the world. Although their new prototypes were damaged by the anomaly, they began to reconstruct them, and fine-tune them, hoping to bridge the gap and find out what had happened.
When they finally bridged that gap, a portal opened on Draco, and through that portal, a man returned to Terra after many years absence. He wasn't a part of the HELIDER project; he predated it, with memories of things that should have lied buried in the mysterious Zero Age. He also knew what Terrans were like, and didn't for a moment trust them with the planet Draco, which he had long considered his home. The dystopia, partially caused by Domino Effect, only heightened those feelings. After a series of blunders, even as the two worlds began to be connected by more and more portals, he sparked off a war between the two planets. He returned to Draco and took the name Deus Exterra, and with that name he fought to prevent tragedy wherever he could by attacking those who did evil. Perhaps strangely, he and Domino Effect never truly became enemies, and would sometimes consider each other friends, but they never were truly on the same side.
This was the Second Age. The long war that was fought began as Terra Vs. Draco, but splintered as both sides understood the humanity of the other. People of both worlds could easily fight together, if they believed in each other. However, the fighting lasted for well over a hundred years, as fear and paranoia ruled. Many people fought for good and stability, and for a long time, they were winning. However, in the end, that painful fear and frustration boiled over, and when at last Domino's equations and knowledge sneaked out, a warrior of pure darkness arose that wanted to destroy everything. In the last few battles, the final seals on both the dragon system and holography were unleashed, all in hopes of defending against the threat.
Insofar as they wanted to defend the world, they failed. The final blow shattered the minds of every person on both planets. Holography was iffy; the Dragon Systems were fragmented or destroyed. However, the humanoid races did not disappear, and the planets did not split apart; many of the surface portals had become truly welded shut. They all struggled for sanity for another century and a half, piecing together the knowledge that had been lost, and struggling just to keep alive. This was the Third Age, and it was hell. Scattered remnants of technology were their best bet for survival, but in addition, people began to awaken "shards" of the Dragon System in their own bodies, shards that required a "key" in order to activate. These shards had could restore sanity... but only enough to awaken a person from madness. If they fell back in of their own accord, oh well.
Long after the end, the Fourth Age would begin. It was a time when the world was recovering--plants returned, animals were reseeded from genomes. It was a world of frontiers and emptiness, marked by new potential--but also marked by struggles, struggles over territory and viewpoints and people, and history and life and death. This was a time when there was no distinction between users of magic and users of technology; they were both inheritances of the past, and there was no longer a division between them, much as the two planets had become one in the minds of the people. Whatever struggles they had, they were mundane ones--criminals and international squabbles, not world wars or attempts at genocide.
As for the future, the time beyond the Fourth Age, that story lies beyond the stars...