Speculation

"This thing is enormous!" Standing on the robot, Swain looked like an ant.

"Even a member of the Giant Tribe would probably look like a child beside it."

What kind of energy could power a robot this massive?

Electricity?

Enel might have been able to do it. In a sense, he was an "endless power source."

Suddenly,

Swain remembered something about Enel.

In the original story,

Enel had reached the moon and discovered an ancient underground city, where he saw two murals.

The story on those murals took place in the Primordial Era.

But was the Primordial Era the same period as nine hundred years ago?

He remembered that Kaido's army of Devil Fruit users included many Zoan Devil Fruit users, and the dinosaur users were classified as Ancient Zoans.

And in Alabasta, Vivi had said the Sandora River's history of irrigation stretched back to the Primordial Era.

That also suggested Alabasta had records of civilization dating back to the Primordial Era.

The palace in Alabasta had been built four thousand years ago, so the Primordial Era had to have been at least several thousand years ago.

When Swain and Vegapunk discussed the legend of Nika, Vegapunk had said Nika was a legendary warrior celebrated by slaves since the Primordial Era, one who could bring people laughter and was known as the Sun God.

Taken together, this suggested that the Primordial Era and nine hundred years ago were different points in time.

The Primordial Era dated back at least four thousand years, to a distant, primitive age when dinosaurs had yet to go extinct.

Humanity was still in a primitive, slave-owning society, while Joy Boy had been active between nine hundred and eight hundred years ago, when an advanced civilization appeared on Earth.

If the Primordial Era came before nine