<human>:  When did the caste system in India start?
<bot>: The caste system in India is a system of social stratification based on birth. It is based on the belief that people are born into a caste based on their ancestry. The caste system is a very old system, and it is still very much a part of Indian society today. The caste system was first established in India around 1500 BC, and it has been in place ever since.