What Are the Layers of Indo-Arian Culture?

There is a possible prehistoric layer of certain corps, ideas, practices, deities that may stem from the indus valley civilization or other prehistoric societies around south asia. Then there is the fundamental vadic layer, which is a set of worship practices and ethical codes that were brought into india by the early indo arian migrants over the course of the second millennium b c e. There is then the classical age, dating from about 500 b c tof hundred a d, similar to what we call the classical era in europe and the mediterranean. And there also was the formation of heterodox philosophies, which generally were called shramana - schools of thought that dealt more with the soul