How was the hereditary caste system closely connected to hindu beliefs in reincarnation?

Karma; in other words, you reap what you sow in your next life. A person's caste was seen as the result of the actions they committed in a past life. It is why Hinduism supported the caste system for so long because they believed that it was the result of Karma and appointed by the gods. Similarly, it's also why many wealthy Hindus refuse to give to charity because they believe that the poor are reaping what they sowed in a previous life. 

So much for "peaceful, loving" Far Eastern religions.

What exactly do you mean 

Ithink that it’s mali