The origin of yoga was lost in antiquities. There are many theories of when did Yoga originate, some think 5000 years ago, and others 2500 years ago, and others think that Yoga originated during the Vedic Age in India. The knowledge of Yoga was passed on orally from teachers to students, and this knowledge was preserved through memory. Following the Vedic age, the long and reach history of Yoga is divided into four periods:

Pre-Classical?

This era was marked by (Upanishad), which explains the teaching of the Vedas. This era also was marked by the writings of the (Bhagavad Gita), in which we learn about the Karma Yoga, which teaches that one should follow the path of one's duty and not worry about the results.

Classical?

The Classical period was marked by (Yoga Sutras) of Patanjali, the spiritual philosophy which could help people reach full human potential. It explained what the Classical Yoga was, and it also explained the path of the Raja Yoga

Post-Classical?

This era was marked by the creation of Hatha Yoga - a strong willful practice of rigorous postures. Many yoga masters created systems of practices designed to rejuvenate the body and the focus of Yoga as a physical practice.

Modern?

This era began at the Parliament of World Religions in 1893 in Chicago, where Yoga was introduced to the western world by Swami Vivekananda, who was then considered the most popular teacher of Yoga movement in the western world.