How did they know how many days were a year in the past?

Question

I know that the seasons were indicators but how did they know precisely to the day how much a year was.

Edit: Copying from a response I made:
“Thanks for the response!
But I still have a doubt cause most of the reponses are to measure it in certain way and wait until the sun goes back to its initial position, and I get how measuring its easy by doing it over a long period of time but the difference between 2 days seems kind of difficult to notice, like when the sun got back to its position and people were like “yeah it looks about the same as how it started” and then they observed the next day and it looked exactly the same, how did they decide a specific day.
I guess my question is more about how they achieved such precission rather than the method”

In: Earth Science

Answer 1

They counted how many days until the sun got back to the same spot in the sky at the same time of day.

There’s lots of ways to do this. e.g. northernmost or southermost sunrise or sunset, maximum altitude at noon, etc.