The History of Yoga
It is very difficult to point with any certainty to the precise origins of yoga, largely because until relatively recently it has been a predominantly oral rather than written tradition.
Indus Valley Civilization (c.3000 - 1700 BCE)
Some claim that yoga originated in the Indus Valley Civilization , pointing for example to depictions of horned deities in what appear to be seated yoga postures as evidence that yogic beliefs were central to that culture. It is difficult though to draw any firm conclusions from these depictions - it could just be that this was a common way to depict a seated posture!
Vedic Period (c.1700 - 800 BCE) and Sramanas (c.600 BCE)
Others believe that yoga has its origins in the Vedic period - ‘Vedic’ being one of the 3 key strands of religion in India (the other two strands were Jainism and Buddhism). But...there are some big differences between the Vedic and yogic world views. For example the Vedic approach was more concerned with enjoyment of life (e.g. appealing to the gods for good harvests) and doesn’t seek freedom from reincarnation - a key tenet of yogic beliefs.
It is perhaps more likely that yoga has its origins in Jainism and Buddhism. Collectively known as the Sramanas, these systems were based around practices of austerity designed to destroy existing karma and limit creation of new karma in order to escape the cycle of reincarnation.
Upanishads (c.800 - 500 B.C.E)
What we do know is that the first recorded mention of yoga as a set of practices is in the Upanishads which were the most recent layer of the Vedas (ancient Indian texts). The Upanishads described meditation techniques designed to strip away layers that mask our true Self as a core of pure consciousness (atman).
The Bhagavad Gita (c.300 - 200 BCE)
The Bhagavad Gita is an iconic and definitive yoga text that forms part of the great epic The Mahabharata about a struggle between warring cousins. It was a revolutionary text because it democratised yoga (which had previously been the exclusive preserve of high class men) by opening it up to women and lower castes. It also denied the need for practices of austerity and renunciation, instead advocating three forms of yoga - jnana yoga (the yoga of meditation and discriminative knowledge), karma yoga (the yoga of action from a place of higher awareness) and bhakti yoga (the yoga of love and devotion). The Bhagavad Gita is a wonderful text to read - we have translations by Swami Gambhirananda and Eknath Easwaran.
The Yoga Sutras of Patanjali (c.200 CE)
Patanjali’s Yoga Sutras systematised the previous 1000 years of yoga into 195 aphorisms, the key premise of which was that we mis-identify our true self with the workings of the mind. Patanjali articulated what is perhaps the most famous definition of yoga to this day: “yogaś citti vṛitti nirodhaḥ” - yoga is the restriction of the workings of the mind. The way to achieve this? Through meditation!
Advaita Vedanta (c.800 CE)
In the 8th Century CE Sankara developed a sophisticated formulation of Vedanta that drew heavily on the principle Upanishads. The key tenets of Advaita Vedanta are that the universe is an illusion and we are all in fact pure consciousness (Brahman). To deconstruct this illusion it is necessary to practice discriminative meditation.
Rise of Tantra (From 6th Century CE)
Tantra was a revolutionary school of yoga that matured between the 9th and 12th centuries CE. It seeks to spiritualise every aspect of our daily lives...including our bodies! In Tantra, the entire universe is a manifestation of supreme Reality (not an illusion as in Advaita Vedanta), with spirit and matter being one and the same thing - which means that everything is sacred and anything can be used as a spiritual tool. This fact allows spiritual seekers to engage in the world mindfully rather than having to renounce it. Tantra gave rise to many sophisticated techniques that work with the body as an access point for higher awareness - these include use of mantras, sounds and visualisation as well as hatha yoga (a key element of which is use of postures, as practiced widely today in the West).
14th Century CE to present day
Following Tantra’s maturation there was very little further development of yogic philosophy, largely due to the influence of Islam and Christianity, both of which started to impose their perspectives on Indian thought.
However in 1893 Swami Vivekananda spoke at the World Congress of Religions in Chicago - he was the first swami to visit America and received a standing ovation from the 7,000 people in attendance. This is often considered a watershed moment - from here the dissemination of Indian philosophy and yoga to the West would become increasingly widespread.
For more about yoga and its history please visit Carlos Pomeda's site or read Georg Feuerstein’s The Yoga Tradition. A really engaging discussion on the history of yoga can also be found on Ryan Spielman’s podcast interview with yoga historian Graham Burns.