evidence: The reason for that decision lay in a new territorial claim by China. As Foreign Policy detailed in Part 1 of this investigation, the Namgung La marks the traditional border between Tibet and Bhutan. Thirty years after China annexed Tibet in the 1950s, Beijing changed its view of that border and declared that a 232-square-mile area of northern Bhutan, lying to the south of the Namgung La, had once belonged to Tibet and therefore was now part of China. That area was the Beyul Khenpajong, a remote and uninhabited region, famous throughout the Himalayas as a "hidden valley," that is exceptionally sacred to the Bhutanese.