These 4 books should give a good flavour on mysterious Tibet.
Tibet, Tibet is a travelogue. Turquoise Roof is an autobiography by a Tibetan aristocrat lady of life in Lhasa pre 1950s.
The Fourteen Dalai Lamas is an account of all 14 Dalai Lamas in chronological order. Tibet A History is a general introduction from the founding of Tibet as a kingdom.