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 asana practice, but also stated that the breathing should be deep breathing with sound. He reiterated this notion in a conference in 2013 stating, "You do normal breath, inhalation and exhalation with sound. Ujjayi breath is a type of prāṇāyāma. This is just normal breath with free flow". In 2014 published on YouTube, Manju Jois dodged the question, "What is the difference between Ujjayi breathing and free breathing?" by saying that "the breathing in Ashtanga should be long and deep with the sound like the ocean". He also states that if you don't make sound, that is okay, too. However