Alberuni's India

"In 1017 CE, at the behest of Sultan Mahmud of Persia, Alberuni, also known as Al-Biruni, travelled to India to learn about the Hindus and to discuss with them questions of religion, science and literature and what formed the very basis of their civilization. He remained in India for thirteen years, his exploration and study of the country gave way to a scholarly work that, in its profound understanding of almost all aspects of Indian life, remained unmatched for eight hundred years."