Vajrayāna Buddhism (Devanagari: वज्रयान; Oriya: ବଜ୍ରଯାନ, Tibetan: རྡོ་རྗེ་ཐེག་པ་, rdo rje theg pa; Mongolian: Очирт хөлгөн, Ochirt Hölgön) is also known as Tantric Buddhism, Tantrayāna, Mantrayāna, Secret Mantra, Esoteric Buddhism and the Diamond Vehicle. Vajrayana is a complex and multifaceted system of Buddhist thought and practice which evolved over several centuries.

According to Vajrayana scriptures Vajrayana refers to one of three vehicles or routes to enlightenment, the other two being the Hinayana and Mahayana.

Its main scriptures are called Tantras. A distinctive feature of Vajrayana Buddhism is ritual, which are Skillful Means (Upaya). They are being used as a substitute or alternative for the earlier abstract meditations.

Although the first tantric Buddhist texts appeared in India in the 3rd century and continued to appear until the 12th century, scholars such as Hirakawa Akira believe that the Vajrayana probably came into existence in the 6th or 7th century, while the term Vajrayana first came into evidence in the 8th century. Prior to the Vajrayana developed the Mantrayana, and after the Vajrayana the Sahajayana and Kalachakrayana developed.

Jetsunma Tenzin Palmo is a Tibetan Buddhist nun in the Drukpa Lineage of the Kagyu school. She is an author, teacher and founder of the Dongyu Gatsal Ling Nunnery in Himachal Pradesh, India. She is best known for being one of the very few Western yoginis trained in the East, having spent twelve years living in a remote cave in the Himalayas, three of those years in strict meditation retreat.

Vicki Mackenzie, who wrote Cave in the Snow about her, relates that what inspired the writing of the book was reading Tenzin Palmo's statement to a Buddhist magazine that "I have made a vow to attain Enlightenment in the female form - no matter how many lifetimes it takes".

Jetsunma Tenzin Palmo was born Diane Perry in the East End of London in June 1943. Although spiritualist meetings were held in her childhood home, she realized at the age of 18 that she was a Buddhist when she read a library book on the subject. She moved to India at 20, where she taught English at the Young Lamas Home School for a few months before meeting her root lama, the 8th Khamtrul Rinpoche. In 1964 she became only the second Western woman to be ordained in the Tibetan Buddhist tradition, receiving the name Drubgyu Tenzin Palmo, or 'Glorious Lady who Upholds the Doctrine of the Practice Succession'. The ordination was as a shramanerika, or novice nun, the highest level of ordination currently available for women in the Tibetan tradition where the bhikshuni sangha has died out. However, with the support of her teacher, in 1973 Tenzin Palmo received the full bhikshuni ordination in Hong Kong, one of the first Western women to do so.