Yoga has been probably the best gift from our ancestors to us. Yoga began in Indian subcontinent during the times when the air was pure, food was organic, and the environment was cleaner. We need it much more now because we have degraded everything at our disposal and hence even after so much development in medical sciences over the years, the incidents of sickness and untimely death have taken a toll on the planet.
The term "yoga" was first used in the Rig Veda – a religious scripture of the Hindus. It dates back to over 50 centuries. It began in the Northern Civilization. It is said that yoga provides the ultimate level of harmony achieved between the mind and the soul. Lord Shiva is seen as the first Yogi of civilization. It is believed that yoga teachings were earlier written on palm leaves and also propagated the same way. But since it was easily destroyed, it started getting documented in the Vedic age.
Yoga was mostly popularized by Swami Vivekanand along the 19th century. Seeing such applaud given to the exercise, the western world started encouraging it vigorously in the 1980s. Currently there is a tiff going on between the US and India regarding the copyright over the yoga postures and Aasanas. India has submitted the documented practices to the associated panel of decision makers but nothing official has been announced yet.