Mahayana Buddhists believe a mystical manifestation of Shakyamuni Buddha taught the twelve-thousand verse Kalachakra tantra in southern India a year after his Enlightenment.  Kalachakra literally means Wheel of Time.  Its tantra offers a complex statement on the nature and relationship of the outer or external cosmos and the inner cosmos (the body's psychophysical elements and vital energies).  These synergise into a purified subtle enlightened mind that is the known as the alternative dimension of Kalachakra.

Although the Kalachakra practice belongs to the class of highest yoga tantra, it is the one such tantra taught openly to the general public.  The present Dalai Lama states: "The higher meditations of the Kalachakra tantra can be practiced only by a select few; but because of past and future events, and in order to establish a strong karmic relationship with Kalachakra in the minds of the people, there is now a tradition of giving the initiation to large public gatherings."