Red-Haired Shanks is the Red-Haired Pirates' captain as well as an Emperor of the Sea in One Piece. He and Buggy were both apprentices aboard the Pirate King Gol D. Roger's ship. He formed his own crew once the gang was disbanded.
Shanks has been a significant background figure since the beginning of the series. His first significant contribution was sacrificing his arm to save Luffy's life, presenting him with the straw hat, and encouraging him to become a pirate. He was also partly responsible for the One Piece protagonist's Devil Fruit abilities.
Although Shanks is renowned for his skill with the sword and his amazing control over Haki, little is known about his goal and his crew's activities. Fans are convinced that he will play a pivotal role in the future.
However, some information regarding Shanks' early life has been disclosed in One Piece Volume 4000000000, titled RED. It is a free volume issued to the first three million attendees of One Piece Film: Red. The figure refers to Shanks' bounty, which is four billion berries.
This volume explains Shanks' background and how he became a member of the legendary Roger Pirates.
Disclaimer: This article contains spoilers.
One Piece Volume 4000000000 reveals that Shanks was found in God Valley
God Valley was an island where Gol D. Roger and Monkey D. Garp joined forces 38 years ago to battle the notorious Rocks Pirates. Their combined force eventually defeated the formidable Rocks D. Xebec. This whole incident was later named the God Valley Incident.
However, the island vanished completely from the earth's face and from maps of the world after the battle. The manga has been unraveling the secrets of the One Piece universe, primarily knowledge that the World Government has attempted to suppress. It seems possible that Oda may finally be delving into the secrets of God Valley this year.
When One Piece Volume 4000000000 was released, an unexpected link between Shanks and God Valley was uncovered. Shanks was born 39 years before the present timeframe, according to the data provided.
Oda prepared a basic storyboard in which he portrayed how the Roger Pirates had discovered some treasure and planned to seize it before the Marine arrived. They did, however, hear a sound coming from the treasure chest, which when opened revealed a boy.
So, 38 years before the present time, when Shanks was only a year old, he was discovered by Roger and stayed with him till his death.
Oda's rough drawings of the scene have been successfully completed by a fan:
According to the timeline described in One Piece Volume 4000000000, Shanks was fourteen when the Roger Pirates were disbanded and fifteen when Roger was executed. It also says that he was twenty years old when he protected the two-year-old Uta from a pirate attack.
There are a multitude of theories that have been put out, one of which is that Shanks may really be Rocks D. Xebec's son, who had protected him by putting him in the treasure box. Readers will have to wait and see what happens.
Oda has yet to disappoint with his revelations, so there might be something grander underlying the character's birth as well as his present objectives.