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 more breaths in difficult postures. Various influential figures have discussed the specific process of breath in ashtanga. Pattabhi Jois recommends breathing fully and deeply with the mouth closed, although does not specifically refer to Ujjayi breathing. However, Manju Jois does and refers to breathing called "‘dirgha rechaka puraka’, meaning long, deep, slow exhalations and inhalations. It should be dirgha... long, and like music. The sound is very important. You have to do the Ujjayi pranayama". In late 2011, Sharath Jois, the grandson of Pattabhi Jois, declared his feelings on the issue, stating that Ujjayi breathing was not done in the