Few details are known about the figures of the emperors, ie strongest pirates in the world by ONE PIECE. If some aspects related to Big Mom's life have been deepened with the Whole Cake Island saga, the same cannot be said of the other three. If you were able to learn more about Shanks with ONE PIECE: RED, now was Kaido's time.
The lord of the samurai island sees his reign coming to an end, so Eiichiro Oda decided to include a flashback of Kaido ONE PIECE 1049. In this way we learned some details of the Emperor's earlier life, with some basic situations.
but right where Kaido was born? Previously it was only known that Kaido was born on an island of the Grand Line. The first pages of chapter 1049 give this answer. Kaido was born in the kingdom of vodka, which has never been mentioned before. The island is ruled by a king and a seemingly very poor people, where there was much violence and submission to the sky dragons, for which a donation had to be paid.
However, Kaido immediately hit the headlines and violently threw himself through it from childhood, and because of this, Kaido's size was immediately high. We'll see if Eiichiro Oda decides to give more information about this island in the next chapters or in a special data book.