How are the central ideas of hinduism and buddhism alike?

For one thing, both believe in Karma and reincarnation and the cycle of life for each soul. Both have a lot of aspects regarding the illusory state of the world and how our senses aren't all that good and that we should separate ourselves from material things. Both feature strong ideas about the connection of all organisms and pacifism and avoiding to hurt others. These are the basic ones but there are more similarities.

The sumerian empire worshipped a lot of natural aspects like wind. the impact on civilization was people abided by rules to avoid displeasing gods and it created a drive in people to be good. i hope this is what you were looking for, as this question was quite broad.