Followers of Patanjali’s Yoga Sutras are practicing Ashtanga or Raja (Royal) yoga, of which there are several different branches. Historically, Hindu tradition divided the paths of yoga into intellectual, emotional or physical paths or “margas”: Jñana, Bhakti, and Karma. In approximately 15th century C.E.
Swatmarama wrote the Hatha Yoga Pradipika (Hatha means force, or determined effort).

B.K.S. Iyengar popularized Hatha yoga in the West through his use of props and tools and precise descriptions of the various poses, making them more accessible.
In the introduction to “Light on Yoga” first published by Schocken books in 1966, Iyengar explains that Hatha and Raja yoga are complementary approaches to the same goal:

“As a mountaineer needs… ropes and crampons as well as physical fitness and discipline to climb the icy peaks of the Himalayas, so does the Yoga aspirant need the knowledge and discipline of the Hatha Yoga of Swatmarama to reach the heights of Raja Yoga dealt with by Patanjali.”