The oldest known Hindu artifact is 28.5 thousand years old, meaning that Hinduism had to have started by at least then, but it is likely that it is much older.
It depends on the religion.
It is the native religion of Japan and was once its state religion.
Judaism did not begin within another religion.
India
Islam
About 550BCE
Polytheists.
It began in India. This religion is the oldest religion in the world.
As the Greeks studied science, how did it begin to change their relationship to their religion and to their gods?
=500 B.C.=
Ireland, where the Celts were.
1500 BC800bc