After the Chinese invasion of Tibet in the 1950s, a chain of human communication was threatened with breaking.
Two thousand five hundred years of continual communication of a spiritual tradition. Twenty-five hundred years ago when Buddhism arrived in Tibet, the native spiritual tradition, Bon was not discarded by the great teacher Padmasambhava, an Indian spiritual adept who is credited with transmitting Buddhism to Tibet (and, according to the linked Wiki, Bhutan as well).
Transmitted. That is an important word.
But first, today is Milarepa Day.
The link is to the Shambhala website (and the Shambhala organization), and will figure into all this later.