2,500 years ago is about 500 BC.

This is quite recent.

It was about that time the Peloponnesian War occurred, which Thucydides and Xenophon documented.

OTOH, I think Siberian peoples then were not advanced. However, here we're talking tattoo and art, which you can imagine being developed more easily, rather than more concrete stuff, such as commerce raiding, building and maintaining hundred of triremes and training the oarsmen and generals to fight them in massed combat, and developing Athens into a city of 250,000 people.