Osten partnered with Rai on a number of India's earliest blockbuster films like Achhut Kanya and Jeevan Naiya.
These movies contributed to increasing the understanding of eastern religions and offered visual splendour and escapism, featuring live elephants in festive decoration and utilising thousands of extras.
The 28-year-old Indian solicitor Himansu Rai came to Munich in search of partners for series of films on world religions.
He had heard that the passion plays of Oberammergau were a showcase for German culture and now wanted to create the Indian equivalent.
On 26 February 1925, Osten and Rai, together with their cameramen, Willi Kiermeier and Josef Wirsching, and comedian Bertl Schultes as interpreter, boarded a ship for India.
There Osten began to shoot his first Indian film, Prem Sanyas – Die Leuchte Asiens-The Light of Asia, the first German–Indian co-production.
The film tells the story of Prince Gautama Buddha, who according to an omen will "follow the sad and lowly path of self denial and pious pain" if he ever faces old age, sickness or death.
In the United States the film lacked success as "motion picture audiences in America do not care to pay an admission fee to see a prince become a beggar.