Void Century

Also referred to as the Blank CenturyThe void century was hinted during the Skypiea Arc, the numbers of date was found in Robin's flashback. The years of this void century rages from 700-800 in the Age of the Sea.

About
This period became known as the blank century because there is nothing left to acknowledge anything that happened, aside from the Poneglyphs which are written in a language that few know how to read.

However, it causes a problem with the known histories of the world as nothing ties up because of that missing period, although most people do not seem to be aware about this information. For example, Nefertari Cobra after being told by Nico Robin about this missing period was completely shocked by its existence and didn't know there were parts of the world history that didn't tie in.

The Great War
The most major event during the Void century seems to be the Great War.

Ancient Kingdom
This kingdom was frist heared in chapter 395 by Professor Clover who tried to tell the Gorousi the real reason why they were afriad of the Void Century. Before Clover can say the name of the kigndom, he was shot.

What little facts are known are that it held great power until the Alliances, who fought against the kingdom managed to defeat them. However tghe details of the events leading up to and how they were defeat remain unknown.

The Alliance
The Alliances are the ancient forces that became the World Government. During the Void Century they fought against the Ancient Kingdom. Who are the Alliance and what are the connection with the Ancient Kingdom reminds unknown as of now aside from the obivous fact that they fought against them.

Birth of the World Goverment
In 800 at the end of the Void Century, the World Government was born and took political control of the entire world, uniting all countries and forming the Counsel of Kings. For the World Government, the events of the void century were better left unknown as information linked to it is considered far too dangerous.

Poneglyph
For the main article, see Poneglyph

Ancient Weapons
Only 2 weapons are metioned but were never shown. The Ancient Weapons known in the story so far are Pluton and Posidon. Each weapon was construction during the void century and so far all mentioned weapons were capable of extreme mass destruction, the complete destruction of entire islands.