One look no further than Vietnam for how the government learned to use intranational xenophobia to manipulate different slices of the public into identifying as separate groups that could then be played off of each other. Since then, there has never been as successful a political movement, because we have been turned against each other by state-driven manipulation. AFAIK, this is well-documented policy intended to “maintain civil order” (i.e. prevent the revolution that is so richly deserved).