The history of yoga starts as early as starting of human life. This could be approximately 5-10000 years old. The period of yoga can be divided into 3:
1. Ancient yoga
2. Classical yoga
3. Modern yoga
1. Ancient yoga: It is around 2000 BC when there were settlements of population around Indus Valley. This was the beginning of Indus Valley Civilization where the Aryans, Indo-European travelers settled and mingled with the local populations and followed a culture which was later on named Hinduism(actually Indus). The followed the Vedas, the direct writings of God. It is the period of Vedas. Vedas are the oldest sacred book of Hinduism. It was a collections of hymns, chanting, songs and rituals. The word Yoga was found for the first time in Rigveda (one of the 4 Vedas). There was more elaborate discussions in Yoga in the Upanishad which is the summary of vedas. At this stage yoga was mostly was for spiritual enlightenment.