Is religion the most basic codification of natural law?

[Viking]

Well much much earlier, but when was it ever not there. That is new.

At some point, they came into existence; and I think it went along with the culture and the norms; who have not always been here either.

hmm... all the so called "pagan" religions seem culturally inclined... meaning based on local customs...
i know from experience Hinduism is based on customs than anything else...

Yes, but I think you will find that all religions are based upon where they originated. Christianity; having judaism as a precursor, a religion with promised land and a chosen people; cannot escape this either. But indeed some religions are more local than others. The "pagan" religions typically originated in a much more "closed" world than today's world religion; a world where the mere notion "world" would be meaningless. Religions necessarily (you can go and have a look for yourself if the thunder god Thor actually is up there with his hammer) always reflect the society they exist in; take scientology for instance.