Why were the hazaras singled out for prosecution?

The hazaras were known to be of Mongol descend, and shia converts. Because they're the only shia group opposed to the sunni group they were thought as of 'lesser being'. The hazaras weren't known much back then, no one would dare to enter their grazing grouds/lands, located in the center of the country and so the pashtuns grew jealous and angry. Today even the government set up by U.S/NATO discriminates the hazara by letting pashtuns to graze on the hazara lands and having the right to shoot the hazara on sight with no punishment.