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​The simple answer…
Human beings use symbols to convey meaning through culture: language, religion, art, etc.
http://i.imgur.com/2FdfnYd.jpg

From the image found in the above link, you can see that all of our cultures began as one in the Middle Paleolithic Period. As the hunter-gathers split up and migrated, many cultures branched off. During the Vedic Period (800 to 500 BCE), a series of religious hymns were published in The Vedas. This was the earliest form of Hinduism, Buddhism and Jainism. The oldest of The Vedas, The Rig Veda is the earliest mention of yoga in the written world. That is why you will find many of yoga’s concepts share commonalities with its Eastern brothers/ sisters from The Vedas.
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During the 19th century, yoga experienced a revival in India. In the 1930s, yoga came to The West. Here is a visual timeline of this: http://www.dailycupofyoga.com/wp-content/uploads/2011/04/yogaflowchart1.pdf .  

According to Richard Rosen's Yoga FAQ: Almost Everything you need to know about yoga- from asanas to yamas,  in 1852, the first English translation was published. Between the 118 years from 1852 to 1970, there were 25 English translations of The Yoga Sutras. From 1970 to the present (2017), there were 88 translations published, 32 of which were published in the last decade alone. Yoga's versatility lends itself as both a science and a philosophy. Today, thanks to the combination of both  results from various studies in modern science linking the benefits of yoga to physical and emotional health and capitalism, yoga continues to spread.  

Other fascinating yoga info pages on yoga and its many reincarnations:
​www.bbc.com/news/magazine-24617961
​www.bigbookofyoga.com/hathayogabook/title-page-hatha-yoga-book-1.php
​www.asia.si.edu/explore/yoga/default.asp