No they haven’t been violently discriminated against for millennia. This is a common colonialist trope spread about India. Your language alone, using Western words like “caste” to describe a system that doesn’t fit that word, is influencing your perception. Caste based discrimination (and all the negative issues that come with it) is very recent, and was nudged into existence by British imperialism, which relied on divide and conquer to control large populations in countries they ruled. Historically Indian separation of these different groups was more like specialization of economic/cultural roles, and did not have the modern sheen of disrespect/classism/discrimination. Please don’t spread ignorant falsehoods like this.