The origin of Yoga has been traced back to somewhere nearly 5,000 years ago. A definitive marker in time is challenging to pinpoint due to the nature of the practices and the passing of sacred texts from teacher to student orally. The intial periods of evolution have been deeply analyzed by mystics and yogis. Most of them determined two main philosophies threads: dualistic or non-dualistic approaches to the multiple paths of Yoga. Stepping on these varied paths/maragas opens one to the vast world of all that is possible when exploring the multiple layers of Yoga.
Yoga's Timeline
2009 The US White House includes Yoga as part of physical fitness activity day for the first time. 
2008 The modern version of acro yoga appears on the scene. Modern – or – Blast from the Past.
2003 
Dogs appear as part of the 1st offerings with animals.
2002 Bikram Choudhury’s attempt to copyright 26 pose series, is defeated by the courts. Setting the precedent that Yoga doesn’t belong to any one person.
2001 Time magazine’s feature article highlights the many benefits and components of Yoga.
1999 Yoga Alliance, a US based non-profit, starts to create a unified credentialing system for Yoga professionals.
1997 
…brings Tantra into the modern Yoga scene
1995 Laugher Yoga is founded
1990’s Birch, West & Baptiste all bring 
to the forefront
1983 Dr. Dean Ornish’s study shows that heart disease can be reversed through diet, meditation, group support, and yoga
1975 Yoga Journal prints first issue
1973 The definition of Vinyasa emerges
1970 On October 5, Lilias Folan, airs her 1st show of Lilas, Yoga and You. After three years on the local PBS station in Cincinnati it went national. She is still around and has a Facebook page!
& Sri Swami Satchidananda gives opening speech at Woodstock. View it.
In 1968, Yogi Bhajan introduced his own brand of Kundalini yoga into the United States
1967 The Beatles in Rishikesh 
1961 T.K.V. Desikachar started working in the Yoga Mandiram ashram with his father.
& Yoga TV with Richard Hittleman airs
1948 Ashtanga Yoga Research Institute is established
1947
After eight years of teaching in India, Indra Devi, leaves for the United States and opens the first Yoga studio in Los Angeles.
1931 
Tirumalai Krishnamacharya, the forefather of modern Yoga, is invited to teach at the Sanskrit College in Mysore. He becomes the teacher of many modern day Yogasana founders.
1918 Sri Yogendraji 
introduces Yoga as a fitness exercise.
1897 1st photo of Yogāsana to appear
1893 Swami Vivekananda 
visits Parliament of Religions in Chicago.(listen to his speech)
1875 Theosophical Society is founded introducing Yoga to high society in NYC.
1840 Sritattvanidhi’s book of 121 images is published as 1st set of Yogasanas.
1836 Henry David Thoreau is 1st self-identified Yogi (part of American transcendentalism, influenced by Yogic ideals)
c. 1400 Hatha Yoga Pradipika is written by Svatmarama 
c. 1100 Hath Yoga is invented by the sages Matsyendra & Gorakhnath (who forms a sect called the Naths, for centuries to come they shepherd through the centuries.
c. 500 Bhagavad Gita outlines ancient principals of Yoga.
The central one being: do ones’s duty & expect nothing in return.
c. 1100-450 Tantra philosophy begins to crystalize. It is one of the first coming from this part of the world to include women.
c. 1005 
Tantra philosophy is clarified by the sage, Abhinavagupta, and a text known as Tantraloka.
c. 200 Yoga Sutras written by Patañjali
Study the Sutras, & gain further insight into the incorporation of Yoga into your life.
BC
c. 600
The Upaniṣads define Yoga as a restraint of the senses, not all of the practices are revealed in this text.
c. 1200
c. 3800-1800
1st poses written on stone tablets
A Brief History Of Yoga: From Ancient Hindu Scriptures To The Modern, Westernized Practice
Yoga comes in many shapes and sizes; it has thousands of interpretations and pathways that lead to spiritual awareness, expanded consciousness, transcendence, or simply physical fitness.
The Yoga Poster: A Learning Tool
A diagram that captures, concisely, all the major aspects of yoga.