The Ancient Kingdom existed long ago in the world ofOne Pieceand fans know that this powerful kingdom was incredibly advanced, composed of the brightest of minds and the strongest of people.Joyboy, who fans somewhat know in the story now, was a part of this kingdom and was likely at the helm of it as well.
There were many powerful races that were a part of the Ancient Kingdom that fans have come to see over the years inOne Piece.While fans have not seen a glimpse of the kingdom itself, its many allies have already been revealed.

8Humans
Notable Character: Monkey D. Luffy
Humans are one of the many races in theOne Pieceworld and it goes without saying that some humans were allied with the Ancient Kingdom. There are many powerful humans that exist in the pirating world right now and the likes of Luffy, Roger, and many others all fall under this race.
They have stood the test of time and fans should absolutely expect them to be a part of the Ancient Kingdom as well.

7Fishmen
Notable Character: Jinbe
The Fishmen are confirmed to be allies of the Ancient Kingdom, given that they had connections with Joyboy. The former mermaid princess was also a very close friend of Joyboy and he also made a promise to them that he would bring them to live life under the sun using the giant Noah.
Of course, Joyboy failed his promise to the Fishmankind, however, this promise will eventually be fulfilled.

6Giants
Notable Character: Dorry and Brogy
Giants are the strongest known race to exist in the world ofOne Pieceand they are certainly allies of the Ancient Kingdom as well. Many secrets about the world ofOne Piecelie on the island of the Giants. Fans have always seen giants on the right side of history as they have been allies of not just Luffy but also Shanks.
The secrets regarding the fourth Poneglyph are also linked to the giants and fans will see all of them being explored soon in the story, which means that they are part of the Ancient Kingdom as well.

5Sky Island Races
Notable Character: Wyper
The winged races of theOne Pieceworld are also known to be allies of the Ancient Kingdom and this is especially true for the likes of the Shandians. They were protecting a Poneglyph and fans already know that Shandorafought against the 20 Kingdomsin a war nearly 900 years ago.
They lost the war, however, the City of Gold was able to survive and, at the same time, their Poneglyph was also preserved. Fans also know that the Skypieans, another winged race, also pray to the Sun God, meaning that they were also allies.

4Minks
Notable Character: Carrot
The Minks are a race of humanoid animals that exist in theOne Pieceworld and they have always been allied to the Kozuki, who themselves are allied to the Ancient Kingdom. This means that the Mink race has always been loyal to the people of the Ancient Kingdom.
They are an incredibly powerful bunch with the ability to use electro from a very young age. In fact, even a childMink can defeat a full-grown human adultwith rather ease.

3Dwarves
Notable Character: Mansherry
Dwarves were only introduced inOne Pieceduring the Dressrosa arc and it was then revealed that they were an important part of the history of the world ofOne Piece.
They were definitely allied with the Ancient Kingdom, given that the previous king Donquixote was incredibly cruel to them. The dwarves are allies of the current Joyboy, Luffy, as well and one should expect them to have been relevant in the previous Great War too.

2Lunarians
Notable Character: King
The Lunarians were known as the Gods of the worldnearly 400 years ago. They likely flourished during the Void Century too and given that they believe in Nika and his return, they most likely were allied with the Ancient Kingdom as well.
Alber, who is the last known trueborn Lunarian that the fans know of, wanted Joyboy to come and save the world, which all but confirms that their race were allies of the Ancient Kingdom.

1Buccaneers
Notable Character: Kuma
The Buccaneer race was recently revealedinOne Pieceand this race appears to be somewhat of a mix between a human and a giant. Of course, this isn’t a race created by the interbreeding of these two races. In fact, it is a race that exists on its own but these people are believed to have the blood of the giant.
This means that the Buccaneers have incredible strength as well as resilience and durability, all the while having a smaller stature when compared to the Giants. They are heavily connected to Nika and know all of his secrets. This is a clear indication that they were allies of the Ancient Kingdom long ago in the past.

One Piece
Cast
One Piece is a Japanese manga written and illustrated by Eiichiro Oda. The series follows protagonist Monkey D. Luffy and his Straw Hat Pirate crew as they explore the Grand Line to find the King of the Pirates' ultimate treasure, the One Piece, in order to become the next king. The manga’s popularity helped it spin off into a larger media franchise, including an anime with more than 1,000 episodes.