Why there was no caste discrimination in ancient India? read details?

I don't know. Perhaps people were more civilised & tolerant in ancient period. Most of people refer Rig Veda & chapter 'Mandal' in that for justifying the caste - ism, perhaps by biased & twisted interpretations, I don't know that too. I've read somewhere in that chapter that if a woman has ten non-Brahmin husbands but if a Brahmin holds her hand after them, he ONLY becomes her real husband b/c a Brahmin has more rights. In the same chapter, it is written that a Brahmin can never be awarded death sentence for whatsoever crime he commits in ANY condition. On this I was told by Brahmins that this rule is applicable on true practicing Brahmins & not just the son of a Brahmin living like 'adharmis' in practice, I don't know finely that too. I'm sorry, if there is any mistake. Please point out any mistake. I'll modify the answer accordingly. I'm not a learned person in this field. I'm a non - expert in that.