During the cataclysm, the planet expanded like a gigantic rubber ball that had been compressed into half its size and then released. Most other planets in the solar system encountered the same issues, although some in Old Areth's solar system had been displaced by early Traveller experiments and now held strange orbits, slightly departed from their companion worlds. The planet, due to its additional mass, had swung further away from the solar system - a good thing, because the star itself had obtained a new companion and become a binary star system. The new world of Areth had two moons, and only Traveller planetary displacement spells cast at suicidal levels of intensity were able to push them far enough away from the planet to prevent them from spiralling inward to collide with it due to its increased gravity. Massive geological upheavals sprayed lava, the new moons combined with massive tectonic shifts caused tidal waves, and over half of the surviving population of the new world died in the process. After the devastation was over, the scattered bands of survivors stood up and wondered what to do next. For many of the unwary Old Areth citizens, so used to their peaceful society, the answer was die. For the world which had irrevocably melded with theirs due to the Travellers' mistake was filled with ancient horrors which had long been either extinct or civilized in Old Areth. The dominant races on the gentle Old Areth were humans, elves, dwarves, halflings, sprites, and the occasional Lesser Dragon - all civilized, on good terms with each other. The new world was veritably crawling with bloodthirsty species which had long ago become either extinct or bred into the mainstream of the other races. Species such as orcs, trolls, ogres, Drow, and the most dreaded of all - the Great Dragon, which had once burned and terrorized Old Areth but had eventually evolved into the Lesser Dragon, a more amicable beast with many of its abilities but lacking their fiery temper and need for carnage. Upsetting the balance of power even more, the magical characteristics of Areth had been changed forever by the combination of the two worlds. Except for the very simplest spells, magic was completely useless and had to be rediscovered in the new environment. Few psionicists were left; all but their strongest or least gifted members had been driven insane by the simultaneous psychic death cries of a planet and a half during the hasty union of the two worlds. Except a few outposts of civilization where the weaker races had gathered for defense, the world of Areth was overrun by primitive races which, once the planet stopped shaking, gleefully undertook the task of butchering the shaken survivors.
But amidst the chaos of the second world, there also came hope. Although the weak intellectuals of Old Areth had forgotten the ways of the sword and the discipline of steel, the second world's humans, elves, and dwarves held weaponry dear to their hearts and cared little for the mumblings of hooded sorcerors. Were it not for the warriors, samurai, rogues, and ninja who came from the second world, Areth's people would have been erased by the tide of predators the Travellers had brought upon them. In the wake of the failure of magic, many Old Arethians dropped the tired tomes of magic to take up broadsword, axe, or katana. Pragmatic to a fault, the Second Worlders rapidly built up primitive defenses in the ways they knew best, fashioning weapons and digging earthworks until their scattered villages could withstand the onslaught of the primitive, bloodcrazed races.
The surviving Travellers, the handful who hadn't been killed during the cataclysm or sustained lethal mana burns pushing the moons away from the planet, quickly agreed that the dimensional displacement spell was far too dangerous to ever attempt again, and were said to have quietly destroyed all knowledge related to it. One of the surviving psionicists was quietly contacted and entreated to purge the dangerous knowledge from their memories, a task which she performed readily. Fortunately for the Traveller Foundation, no one outside of their circle knew that they were responsible for the cataclysm which swept their world - except for the psionicist, who is said to have taken the knowledge of the Traveller incident to her grave.
After the initial upheaval and chaos, the world settled into patterns which were a mixture of what was normal for both worlds. No one quite knew what had happened, but they were determined to continue on with their lives in whatever fashion they'd learned to accept them. The first few decades were a hard time of constructing fortresses and forging communities. In the forests and mountains, the bloodthirsty races propagated until they became legion, and the hardy Second Worlders built strong cities without the aid of the crippled magical industry. The first spells to be relearned were the spells involving warfare, which had come to mean survival as the fast breeding orcs and ogres assaulted their strongholds. In the days of Old Areth, war itself had become unthinkable, and the knowledge of how to wage it magically barely existed. The scattered members of the various Foundations slowly began to pull themselves back together - there were Travellers, Psionicists, Healers, Conjurers, Elementalists, and the newest foundation, the Warlocks. The various foundations eventually met on top of a mountain and decided to create a new city - the city of Shuma. Located slightly beneath the top of the mountain, their dream was to place the Foundations close together in order to share information and bring back the glories of Old Areth. The Second Worlders noticed that Shuma becoming a mecca for discovery and learning, and a number of their fighters' societies moved their headquarters there as well. Although nobody knew what'd caused the cataclysm bringing their worlds together, there was an invisible tension between the inhabitants of the worlds. Old Arethians were thought of as weak and effeminate, and the Second Worlders were thought of as brawny barbarians, barely more sophisticated than the beasts they kept at bay with their horrific blades.
Status quo established, at least for the time being, the Old Arethians and Second Worlders regained their footing and began to build a new life together. And so began the Second Age of New Areth.