20 (((tribes))) work together to take down the most technologically advanced, most powerful nation in the worlds history. The tribes erase all mention of the nations history, instead choosing to create a fake foundational myth to build a new unified "World Government" in which the leaders and the descendants of those 20 (((tribes))) sit on top of the clouds in a royal city and rule over.

All who learn the true history of the world are assassinated and if the threat is too big a "Buster Call" is invoked by the World Government Navy in which they nuke an island killing its entire population to stop the spread of the information.

A group of lawless pirates work together to unravel the mystery of the world and ultimately take down the 20 (((tribes))) bringing prosperity and peace to the world once again after 1000 years of rule by the (((tribes))) who live in their palace above the clouds.

The leaders of this ancient "Great Nation" were the most advanced people in the history of the world using technology that even the greatest scientist in the world Dr. Vegapunk can only crudely imitate. However this great nation had one fatal flaw, their ideology. Their ideology prevented them from endorsing mass genocide so when the 20 (((tribes))) started the war against this Great Nation the military leaders and the political leaders of this Great Nation chose a war of attrition, believing that their technology was so superior to their foes that they could continue it indefinitely.

And indefinitely it did so continue, for over 100 years known as the "lost century" in One Piece lore in which the 20 (((tribes))) were badly beaten back but over the course of generations the 20 (((tribes))) slowly changed their tactics from open warfare to psychological and financial warfare against the Nation.

Eventually they managed to get their own (((tribe))) into positions of power within the Nation abusing discrimination laws and that is how the ultimately took it down - from the inside out.