The history of modern postural yoga is unusually well documented and unusually contested.
The forms that dominate practice today, sun salutations, flowing sequences, the long precise holds of the Iyengar method, were assembled in the first half of the twentieth century, above all at the palace school of Krishnamacharya in Mysore, whose students Iyengar, Pattabhi Jois and Indra Devi carried the method worldwide. Mark Singleton's study of the period argues that these sequences drew substantially on European and Indian physical culture, gymnastics and military drill circulating in India at the time, alongside genuine hatha yoga sources. That argument is accepted by many scholars and rejected by many practitioners and by some Indian scholars as an attempt to write India out of its own tradition. It is a live dispute. What is not disputed is that the specific sequences are modern, and that hatha yoga is not.
What followed is not contested at all. Yoga became a global industry, largely secular in presentation, commercially dominated by studios in wealthy countries, and in most of its forms detached from the ethical limbs entirely. The Indian government has responded with institutional promotion: a national ministry with yoga in its remit, an International Day of Yoga at the United Nations from 2015, and a large documentation project intended in part to prevent postures being patented abroad.
Two objections now run in opposite directions. Some Hindu organisations campaign against what they describe as the appropriation of yoga and its severance from its religious source. Some Christian and Muslim authorities instruct their members not to practise it on the ground that it is inescapably religious. Both objections are sincerely held, both have a case, and they cannot both be right.