Asana "Hatha Ratnavali" provides a list of 84 asanas, describing some of them. In the 20th century, Tirumalai Krishnamacharya taught a new system of asanas, incorporating systems of exercises as well as traditional hatha yoga, to influential Indian yoga teachers including Pattabhi Jois, founder of Ashtanga vinyasa yoga, and B.K.S. Iyengar, founder of Iyengar yoga. Together they described hundreds more asanas, revived the popularity of yoga, and brought it to the Western world. Many more asanas have been devised since Iyengar's 1966 "Light on Yoga" which described some 200 asanas; some 300 were created by Dharma Mittra. Asanas have been claimed
Ashtanga vinyasa yoga and never taught by Sharath. However most of his teachers who claim to have been taught by him will teach the above methods, exercises, & postures, even though none of what they teach is part of the Ashtanga method of instruction under Sharath. Pattabhi Jois also did not require students to independently drop back and come up from back bending before progressing to the 2nd series. Sharath changed the requirements, and has now made this mandatory. However, it is important to note that Pattabhi Jois was the founder of the system, and taught each of his original students differently, instructing