“He felt satisfied,” she said. “Even at the end, even a few weeks before, he said, ‘I’m satisfied with what I’ve done.’ He took yoga to the world. He knew that.”

Bellur Krishnamachar Sundararaja Iyengar was born on Dec. 14, 1918, into a poor family in the southern state of Karnataka. The 11th of 13 children, he was born in the midst of an influenza outbreak. Three of his siblings died before reaching adulthood, and he watched his father, a teacher, die of appendicitis when he was 9 years old. Mr. Iyengar himself contracted tuberculosis, typhoid and malaria; by the time he began studying yoga, at 16, he was painfully frail.

“My arms were thin, my legs were spindly, and my stomach protruded in an ungainly manner,” he wrote. “My head used to hang down, and I had to lift it with great effort.”

His first teacher was his brother-in-law, a Brahmin scholar who had set up a school of yoga at the Jaganmohan Palace, and who sometimes denied his student food if his performance was deemed inadequate. Mr. Iyengar, then a teenager, was the youngest member of the Maharaja of Mysore’s entourage, and was asked to demonstrate his ability to stretch and bend his body for visiting dignitaries and guests.

Mr. Menuhin, who visited India in 1952, heard of his practice and penciled him in for a five-minute meeting, and was so instantly impressed that the session went on for more than three hours. Mr. Iyengar recalled, in an interview with CNN, that “the moment I adjusted him and took him, he said, ‘I’ve never felt this sense of joy, elation.’ ”

The violinist later brought Mr. Iyengar to Switzerland, where he introduced him to other prominent Westerners who became his followers. In his first visit to New York in 1956, Mr. Iyengar said he encountered little interest in yoga. It was not until the next decade that he began to attract crowds.