Twenty Kingdoms

Clover: If we assume those people were wiped out by some "enemy," it means those enemies should have survived later in history. Coincidentally enough... 800 years ago, at the end of the Lost 100 Years, was the precise birth of today's "World Government." If the enemy of those eradicated peoples is our World Government.

Clover, Chapter 395

Pappag: Because they have the blood of the Creators in their veins...... Eight hundred years ago, a group of twenty Kings... ...formed a mighty organisation known as the World Government.

- Pappag, Chapter 497

The 20 Kingdoms or known as the Ancient Alliance are the 20 kings of their kingdoms combine to become an Ancient Alliance that became the World Government. During the Void Century they fought against the Ancient Kingdom, by 800 the Alliances became the World Government. The World Noble are decendent from these kings.

Frist metioned in chapter 395 by Clover, they were fully explained 102 chapters later by Pappag. Why the 20 Kingdoms overthrew the Ancient Kingdom is a mystery.