When all humans are having Red blood, why Brahmins hats Dalits / backward class?
The terrible caste system was invented in order to protect the white Brahmins from polluting their sacred whiteness with black blood. You had to marry and to labor in the caste into which you were born. The lines were clearly drawn and on one was allowed to move from one caste to another by marriage or trade. The mechanism of the caste system is tied to the Hindu theory of soul-transmigration in which your rebirth determines your caste. Your rebirth was predetermined by your karma. Your karma was in turn was determined by how you lived in your past life. For example, if you were born with a dark skin to untouchable parents, your life of misery and poverty is your punishment for being evil in your previous life. In other words, you are getting what you deserved. The poor, the sick, the disabled, the dark-skinned, etc. are what they are because of their own fault. The deserve their suffering because they did something bad in a previous life and their karma has caught up with them.