365 day calendar

Hello,
My name is Andres and this is the first time I am posting on this forum. I have a question that sometimes bothers me.Does anyone know who where the first People/Civilization to use the 365 day calendar? And how many days are there in the Roman calendar and the Jewish (old) calendar?I have seen some topics on the ages of Biblical characters, but it does not answer this question specifically.I was just wondering to help me understand how people can think the earth is only 6000 years (365 day year) old.

Thank you for the responses.For some reason, I had always believed that the 365 day calendar was not so old, although apparently not.Just one more thing, it the romans used a 365 day calendar, why does the dates related to Jesus change every year(except for X-mas): Holy week changes, the day he went into the desert changes. If the calendar was almost the same as ours, why not use a fixed date?

Ach so!!So at least the romans (after J.C.) and the Egyptians before them used a 365 day calendar.Thank you all for the information.