Hatha Yoga Pradipika Yoga Swami Svatmarama

Possibly the oldest extant text about Hatha Yoga, The Hatha Yoga Pradipika was written about the 15th century.
Written in the 16th century by Swama Svatamarama, this book is concerned with the physical postures and breathing exercises of hatha yoga. It also provides detailed information about the Kundalini, the divine force or energy which is awakened through the practice of yoga.