空白の100年

The Void Century is a century-long gap in recorded and archaeological history, the study of which is forbidden by the World Government. The events of this period are so important and relevant that by learning them, one is said to become aware of the "true history" of the world.

These events occurred 800 to 900 years before the current storyline. It was hinted at during the Skypiea Arc; the dates were seen in Robin's flashback.

This period became known as the Void Century because there is nothing left to acknowledge anything that happened in it, aside from the poneglyphs which are written in a language that only two living people 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. Though many seem to know there is a gap in the historical record, virtually everyone is unaware that filling in this gap is possible. For example, Nefertari Cobra, after being told by Nico Robin about this missing period, was completely shocked that a way to "tie the threads of history together" existed. The fact that filling the gap is possible was proven when "Dark King" Silvers Rayleigh revealed that the Roger Pirates discovered the true history.

The true history of the world apparently contains secrets so dangerous that those who are aware of them, including outlaws, are highly reluctant to talk about them. The Roger Pirates and Edward Newgate did not reveal to the public what lies hidden at Laugh Tale and Kozuki Oden did not reveal to his followers the true history because he considered it a burden. Silvers Rayleigh offered to tell the true history to Nico Robin, but warned her that the way she was then, she would not be able to do anything about it. Also any knowledge of the true events of what happened in the Void Century is considered a death sentence and holding such knowledge is liable to death in the eyes of the World Government, regardless of the affiliation of the person knowing it. Even entire nations will be destroyed and erased from existence should even a single person attempt to learn anything about the Void Century, as the World Government is not shy on killing innocents and get rid of nations which attempt to learn anything about it. The World Governemnt would not even shy from destroying their own property just to destroy anyone who has an affiliation with the Void Century, whether they know it or not. In fact, all three canon Buster Calls were initiated at least in part due to knowledge pertaining to the Void Century.