Illegal immigration to Bhutan
On January 6, 1989, the Bhutanese king proclaimed a policy of “One Nation, One People.” This royal edict, called the Driglam namzha, states that all Bhutanese have to dress and speak like Drukpas. Bhutanese citizens of Nepali descent were deemed illegal immigrants.
Source: Wikipedia — Illegal immigration to Bhutan (CC BY-SA 4.0)