The Laotian Communists made a bid to exterminate the Hmong then settled into harassment and persecution which continues. The Vietnamese Coommunists have treated them and the other mountain people as we treated the Indians in the 1890s. The problem is further complicated by the rapidly ongoing conversion of the Minorities in Viet Nam to Christianity. The Communists are quite nonplused and go through cycles of persecution and trying to confine them to fixed locations. There is always "unrest" in the minority areas.
Aren't Hmong related to the Montangards or 'yards as we used to call them? Fierce warriors, IMHO.