Poneglyph

"Poneglyphs" (歴史の本文 (ポーネグリフ) Pōnegurifu, literally translated as Text of History, Ponecliff in 4Kids dub, and Ponegliff in the VIZ media translation) are mysterious stone blocks with history inscribed on it as strange letters and are scattered among the islands of the Grand Line. It is said the only one in the world that can read it is Nico Robin. The first Poneglyph appeared in Chapter 202 and Episode 102.

About
I have come here and will lead this passage to the farthest ends of the world.

These blocks are inscribed with the script of an ancient language. Each one tells a piece of a history long forgotten. This history includes the mention of (at least) two weapons of mass destruction: Pluton and Poseidon. There are two types of Poneglyphs: the ones which carries information to reach the other Poneglyphs and the stones which carries the records of "True History". Only when the stones are read as one, will they fill in the Void Century of the world.

The stones are left in the guardianship of the ancients descendants, who guard them from people who seek to destroy them. Only when the stone has been read by someone willing to take the read passage to the ends of the Earth, are those guarding them allowed to be free of the burden. In order to prevent these historical facts from being lost forever, they had carved them into these Poneglyphs, which are indestructible.

It is against the law of the World Government to research and decipher Poneglyphs. Regardless, to reach and decipher the Rio Poneglyph is the ultimate goal of Nico Robin. Robin states that in order to progress forward, one must take with them the passages they have read from the Poneglyphs they have encountered in their travels to Raftel. It has also been revealed that Gol D. Roger was able to follow the passage because he could hear "the voice of all things". He apparently managed to uncover the path. Roger's First mate more to say his Partner, Silvers Rayleigh, mentions that he knows what the Void Century is and solved the mysteries of the Poneglyphs. He admits that saying what it is would take away the impact or any further interpretations of the lost history. He tells Robin to search out the Poneglyphs and draw her own conclusions, regarding the history.

Arabasta Poneglyph


There is one Poneglyph in Arabasta, the one that is found in the underground passage of the temple in Alubarna. It's the first Poneglyph in the series.

The Poneglyph tells the location of Pluton. Nico Robin never wanted to give Crocodile the ancient weapon so she lied by telling the history of the land which is not found in the Poneglyph. Robin was looking for the True History, not Pluton, so she lost her will to continue on. However, she was saved by Luffy.

Shandora Poneglpyh
Keep thy motives in heart, with closed mouth. We are those who will weave history with the Ringing of the Great Belfry.

The Poneglyph of Shandora is located in Skypiea. Robin discovered that each location of the Poneglyphs held not one but two Poneglyphs. The first Poneglyph has a message to finding the second Poneglyph, while the second Poneglyph held the message of the lost century. Skypiea's first poneglyph was located in a set of ruins Robin found in Upper Yard. Skypiea's true Poneglyph was located in Shandorian Golden Belfry and it revealed to Robin another dark secret. This Poneglyph spoke of how to locate yet another weapon, Poseidon. Gol D. Roger had also previously found this Poneglyph and left a message encouraging anyone who could read the Poneglyphs to continue searching for the lost history. The Shandians were left to guard the Poneglyph but over time as events in Skypiea played out they forgot about its existence. After Robin informs them that the stone has been read, she essentially freed them from the burden they carried over the centuries.

Ohara Poneglyph
Located in Ohara, this Poneglyph includes information about the Lost Century--among other things, it includes the name of the lost civilization, though it has yet to be said what the name is. The World Government considered the archaeologists studying it dangerous and used the Buster Call to destroy the island, Nico Robin being the sole survivor. It is unknown if the Poneglyph survived the attack. However, given that Professor Clover stated the Poneglyphs are inscribed on "indestructible" stone, this is likely.

Rio Poneglyph
According to Robin, the Rio Poneglyph (真の歴史の本文 (リオ・ポーネグリフ) Rio Pōnegurifu) is the message carried by all the Poneglyphs along the Grand Line. It contains the true history of the One Piece world (including the "Void Century" that is forbidden to be researched.) In order to find it, one must take all other passages from the other Poneglyphs with them on their travels, and it is only completed upon reaching the end of the world, in other words, the island of Raftel. Gol D. Roger seemed to have accomplished this task, according to Rayleigh, though it is uncertain if the other members of the Roger Pirates (i.e. Shanks, Buggy) know the world's history.

Trivia

 * The first artifact to actually be recognized as a Poneglyph was seen in Arabasta in Epidsode 123. However another Poneglyph was seen in Episode 102, this one also in Arabasta, when Luffy, Zoro and Chopper were lost in the desert and fell into the ground in an ancient ruin where a Poneglyph was seen half buried in the sand. It bears no significance to the series since it was found in a filler episode.