Although the term hatha is often translated as “force,” hatha yoga is usually associated in the West with a gentle, traditionalist approach to yoga postures in distinction to more athletic Western varieties. Premodern Indian hatha yoga, however, was a complex group of bold and sometimes dangerous tantric practices that went well beyond asana and aimed to restrain and harness the vital energies of the body for the ultimate purpose of spiritual liberation. That group of practices was thought until recently to originate in Hindu tantra, but Mallinson and others say there is mounting evidence that they actually originated in Indian Buddhist tantra, or Vajrayana.


Source: Is Yoga Buddhist? The Buddhist Roots of Hatha Yoga