I'm just wondering about the Void Century in One Piece. What happened during those years. The World Government came to be by taking down the mysterious KINGDOM. I really wanna know the name of that kingdom. Can anybody guess or give e something that would put me at ease? Thanks
The events during the Void Century has not yet been revealed, so for everyone it still remains a mystery, except for the Roger Pirates who have read the Poneglyphs and discovered the true history which the study is forbidden by the World Government.
As for the name of the Ancient Kingdom, its true name is a mystery, as the Gorosei ordered that Professor Clover be shot before he could speak its name.
The only details revealed so far are:
You can read more about it here.
They didn't actually reveal anything yet, but there have been hints in the arcs of Skypiea, Robin's flashback arc, and fishman island.