As a Yoga teacher for 28 years in many forms including classes , workshops, retreats and teaching introductory courses on the history, philosophy and culture of Yoga I can write broadly on this subject including on practice, philosophy, theory and culture.
More information on my Yoga teaching and work here
Blogs on Yoga:
Yoga in Chiang Mai and my story of 30 years of practice.
A very (very) short Introduction to the History and Philosophy of Yoga.