The Longest Journey
Mountainous central Asian country in which Brian Westhouse found himself with Manny Chavez in the Winter of 1934 (before Chinese occupation). After Chavez pulled Westhouse from a snowdrift, the latter spent 3 months in a monastery before crossing the Divide to Arcadia. It is not known how Westhouse, a non-Shifter, managed to cross the Divide, but given Tibet's modern reputation as a land of mysticism it is possible some Buddhist ritual was involved. Something seems to have gone wrong, however, as he ended up being stuck between worlds for 261 years.
The prologue to Dreamfall concerns Brian's 'Shift' from the monastery, and confirms that he did take part in a ritual conducted by Buddhist monks, although the nature of this ritual is uncertain. He comments that the Superior Lama has taught him many things, although whether these are your stock-in-trade Buddhist wisdoms or facts concerning Arcadia is not revealed. Immediately before his ritual he overhears two monks whispering that he is the perfect candidate, and that the "undreaming will be unleashed". It is possible that these two monks represent a rogue faction within the monastery, or that the entire monastery is hiding something from Westhouse.
Curiously, the date for Brian's time in Tibet is given as 1933 in Dreamfall. No explanation has yet been given for this, and it may simply be another inconsistency between games. It has been remarked that 1933 marked the year of the 13th Dalai Lama's death, and so the year of Brian's 'Shift' may have been moved to capitalise on this more significant date.
We still have not heard anything regarding Tibet in the 23rd century.