Swami Sivananda, born 1887, died 1963 at age 76. He was a contemporary of Krishnamacharya through most of the 20th century but passed away 25 years before Krishnamacharya.
Sivananda was less well-known than other Indian masters, principally because he left his home town of Rishikesh only twice and never left India. However, he was a prodigious writer, producing more than 200 books on yoga and philosophy. He covered yoga in great breadth, including hatha yoga, which is the focus here.
In 1939 Sivananda published Hatha Yoga, in which he wrote, “The subject Hatha Yoga is a systematic course of exercises. It deals with Shat Karmas [kriyas -- purification methods], Asanas, Pranayama, Mudras, and Bandhas, and exercises on concentration and meditation.” A classic definition of hatha yoga.
Hatha Yoga includes descriptions and directions, plus a few illustrations, of 25 asanas. 8 pranayama exercises, 22 mudras & bandhas, and 6 kriyas are described. There is a section on energy, including the 7 main chakras. The book concludes with two lists of asanas, mudras, and bandhas for routine body development. Hatha Yoga has a clear link to the ancient texts like Hatha Yoga Pradipika and Gheranda Samhita.
Yoga masters Krishnamacharya and Iyengar promulgated large numbers of asanas. Krishnamacharya ended up with more than 120, exceeding the standard 84 mentioned in ancient texts, and Iyengar described 200 asanas. Sivananda too continued to develop asanas, as did his students, and the Thirteenth Edition of his book Yoga Asanas in 2004 contained a list of 277 asanas, 80% of which are only named, not described.
Sivananda moved on to his next life before the advent of the Internet, and he left behind a void. The void was filled by several devotees with different approaches. Two of the major websites created by such devotees are www.sivananda.org and www.dlshq.org. Other websites are maintained by other adherents to Sivananda yoga. All of the websites are basically contemporary interpretations of Sivananda; some sites more than others provide access to Sivananda’s actual writings and teachings.