From what I gathered in non-fiction: they were building a giant 9 story ziggurat that was so big and such culture blend of people that it was named "Babel" which just roughly means "confusion".
The fictional religious story seems to twist this into some xenophobic shit as always.














Which apparently happened a lot, like https://en.wikipedia.org/wiki/Fidenae - 20,000 people died, insane. That was quite normal in the ancient architecture sadly.