Lahiri Mahasaya in the context of "Paramahansa Yogananda"

Kriya Yoga (Sanskrit: क्रिया योग) is a yoga system which consists of multiple levels of pranayama, mantra, and mudra, intended to rapidly accelerate spiritual development and engender a profound state of tranquility and God-communion. It is described by its practitioners as an ancient yoga system revived in modern times by Lahiri Mahasaya, who claimed to be initiated by a guru, Mahavatar Babaji, circa 1861 in the Himalayas. Kriya Yoga was brought to international awareness by Paramahansa Yogananda's 1946 book Autobiography of a Yogi and through Yogananda's introductions of the practice to the West from 1920.

Mahavatar Babaji (IAST: Mahāvatāra Bābājī; lit. 'Great Avatar (Revered) Father') is a legendary immortal yogi and guru, who is said to be living in the Himalayas. He is said to have taught multiple revered historic yogis, including Lahiri Mahasaya (1828–1895). Babaji first became recognised through the writings of Paramahansa Yogananda, who devoted a chapter of his Autobiography of a Yogi to Babaji and founded Self-Realization Fellowship, a modern yoga movement that Babaji is associated with. The cave where Babaji met Lahiri Mahasaya, located near Ranikhet, is now a tourist attraction and place of pilgrimage in India.

There is little historical information about Babaji. According to Yogananda, Babaji has intentionally kept his birthplace and birthdate a secret.