In an otherwise quiet part of the galaxy, the Gods created a world. Rather, the gods found an important world and filled it with people that could thrive there. It wasn't the first world, it wasn't even the thousandth world, but it would be the next to last. They named the world Adin, and it was a paradise.
They taught these people how to use their gifts, innate abilities to shape the world around them through the manipulation of matter and energy. They taught them agriculture, law, art, currency, empathy, writing, love, medicine, astronomy, and the mysteries of the waters, the metals, and the plants and animals.
A small group of people were granted immortality, to be divine rulers over the Five Nations and to serve as demi-gods, each with their own Edicts to maintain an incorruptible record of the teachings of the Gods.
The Gods asked for very little in return. They wanted the love and admiration of the people they had created, and they wanted the people to sacrifice to their Gods some of the special elements that could be found on this world. The people were industrious and loving, and they provided more than the Gods asked for.
Soon, the Gods asked for another sacrifice. For reasons only they understood, the Gods had to travel to another nearby world for a short time, but they would return to complete their work on Adin. They asked the Adinites to provide them three hundred of their most skilled shapers to accompany them to the stars, and when they returned after a few years the chosen would be given immortality for their service. Selecting only three hundred out of the thousands who volunteered took the span of an entire year.
While the Adinites celebrated their heroes and prepared them to leave, the Gods set about changing their Temple in Heaven to sustain the extra passengers. They forbade the Adinites from exploring beyond their Five Nations while they were gone, claiming hidden dangers still lurked on the world outside of the areas prepared for them. All would be made clear, including their ultimate purpose, after the Gods returned with their three hundred immortal heroes.
They never returned.
In the centuries that followed, few answers were found. Faith rose and fell, and rose again countless times in all corners of the Five Nations of Adin. Prophets claimed secret knowledge that never brought results. Zealots thought they were being tested, or had already failed. Scholars invented dates based on arcane math that claimed the people had misinterpreted the Gods' words, and that this date or that would mark the actual return of their beloved Gods. Those dates came and passed with no signs from above. Trinkets and garbage that people claimed were left behind by the Gods were elevated to the status of artifacts, including many that were later proven fakes.
As Adinite civilization continued to thrive and grow, one particularly forbidden area of land proved too exciting not to explore. Situated between the other Nations, sailors had traveled along its coast for hundreds of years without spotting anything dangerous. Diminishing faith and increasing curiosity finally led to the exploration, mapping, and settling of a new, sixth Nation. They found abundant resources there, and fertile lands. They found nothing more dangerous there than could be encountered elsewhere in Adinite lands, and people wondered why it had been forbidden to them.
Several years passed until someone found the answer. A survey team that was mapping out metal deposits in the mountains deep inland stumbled across an enormous vault of technology left behind by the Gods when they refitted their ship. Included was a message for the Adinites, left by one of the more rebellious Gods in case they were delayed in returning. If they had gotten this far, the message said, they were likely to explore the far side of the world next. There they had left something else important behind, not technology but several other species the Gods had stored on their ship, beings created for previous worlds they had visited. The Adinites would vastly outnumber these small tribes, and they were not designed for long-term survival on this world. Therefore, the Adinites should treat these other peoples with care and compassion, realizing that they were all creations of the same Gods.
Less than a month later, while a small group of enlightened individuals were still debating what to do with this information, the Five Nations were attacked by a well-prepared horde from across the sea. Hardened by battles between the orphaned species as they had discovered each other on the far continent, each believing they were the chosen and beloved of the Gods, they had fought tooth and nail for centuries. They had finally come together as a conquered alliance under the leadership of the Udug, a rabidly aggressive species that had won their lands through savagery and sheer numbers. With the help of those they had enslaved, which included stranger beings like giants and shapeshifters, as well as a bioweapon they called Kudz, the Udug decimated one of the nations without much effort. They chased the survivors across the oceans and laid siege to the other nations from their superior ships, cutting the nations off from each other for years.
At great cost, the Adinites pushed back and eventually defeated the Udug and their allies after duplicating many of the godly artifacts they had discovered, and repurposing some as weapons.
After the war, Adin entered a technological golden age. Golems, airships, powerful computers, and other wild discoveries copied from the vault's artifacts bring swift advancements to the whole world. The defeated orphan species agree to a fair peace, and all of the Gods' children now co-exist together on one happy, united world.
At least, that's what the history books tell us...