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 the teacher is to guide as well as provide adjustments or assists in postures. In other locations, twice per week Mysore-style classes are now substituted with led classes, where the teacher takes a group through the same series at the same time. The inclusion of two led classes per week was only included in P. Jois' senior years. Usually an Ashtanga practice begins with five repetitions of Surya Namaskara A and five repetitions of Surya Namaskara B, followed by a standing sequence. Following this the practitioner begins one of six series, followed by what is called the closing sequence. The