The indo-europeans were the early speakers of the indo-european languages.
The indo-europeans ultimately derive from the proto-indo-europeans, AKA PIEs.

The indo-europeans are very relevant to paganism because they created
five different popular branches of pagan religion, namely germanic paganism,
celtic paganism, greek paganism, roman paganism, and vedic paganism.

The proto-indo-europeans were not a single group, but two different groups- the R1a PIEs and the R1b PIEs.
The two groups were racially near-identical, and had languages that were similar but not identical.
There were major differences between the religions of the two groups.
The R1a PIEs originated in the northern part of the pontic steppe.
The R1b PIEs originated in the southern part of the pontic steppe.

The racial type of the PIEs is called "nordic".
The nordic race is characterized most prominently by the absence of
visible non-homo-sapien admixture (from neanderthals, erectuses, etc), like the cro-magnons.
The major difference between nordics and cro-magnons is that cro-magnons are more robust.