The pilgrimage to Kumbh Mela is the largest gathering of people in the world. Every 12 years, millions come to the holiest place in India - where two great rivers meet. Discover how and why it happens through the eyes of three people: one of Hinduism's five pontiffs, a rupee billionaire pilgrim, and the man who organises this mega-event.

For centuries, semi-nomadic Arabs have brought camels along the '40-day road' from central Sudan to the camel markets of Egypt. Follow one group as they make the arduous 800-mile trip across great stretches of desert, evading thieves and battling sandstorms to reach the Nile.

There are only 150 Mehinacu left in the world. They live in one village in the middle of the Xingu Reserve in Central Brazil. Forty years ago they were first contacted by the 'Whiteman' in the guise of Leonardo Villas-Boas, the celebrated anthropologist who established the Indian Reserve for them and neighbouring tribes. Their culture has been protected but their psychological well-being is less clear.