Diplomatic action
The leaders of all five empires gathered, and one by one signed the Heavens Treaty, ending the war between them all.
While it isn't clear why each empire agreed to end the war, whether it was due to mass loss of lives, destruction of lands, weariness, or something else unmentioned, the fact remains that the conflict had effectively stopped during the year 1002 BD. Between 1002 and 1000 BD they appear to have focused on deciding what would go into the treaty, contracts and agreements, as well as potential alliances should the treaty be broken, trade routes, and so forth. Beyond ending the seemingly endless war waged between the five empires, this is also the very first official declaration of a global calendar, as they ensured to sign the treaty at exactly midnight on the first day of the first month. Many theorize it was their way of showing every future generation that they were truly ending their conflict once and for all.