I don't remember where I read this but I think the Romans got their calendar from Mesopotamia and it was based on a configuration of the sky from a few thousand

I don't remember where I read this but I think the Romans got their calendar from Mesopotamia and it was based on a configuration of the sky from a few thousand years BCE. That configuration drifted so that's why we ended up here. I think the original January (or whatever it was called) was the start of spring.