Joseph Tiefenthaler (or Tieffenthaler or Tieffentaller) (August 27, 1710 - July 5, 1785) was a Jesuit missionary and geographer active in India during the latter half of the 18th century. Tiefenthaler is considered to be India's forgotten geographer because his significant cartographic achievements in India are often given second place to Rennell's slightly later work. Tiefenthaler was born in Tyrol, then a province of the Austrian Empire. As a young man he studied in Spain before joining the Jesuit order in 1729. The Jesuits sent Tiefenthaler to India where he was established as Rector of the Jesuit High School in Agra. In 1759 the Jesuit order was expelled from all Portuguese controlled areas in India forcing Tiefenthaler to flee to the north. Tiefenthaler proceeded to travel extensively in northern India eventually following the Ganges to Calcutta, which had just been established as a trading center. During his travels he dedicated himself to correcting the geography of the country. Using little more than a quadrant Tiefenthaler corrected the coordinates of countless cities and temples. Tiefenthaler eventually compiled his research into two insightful works, Descriptio Indiæ and Cursus Gangæ,. He also made liberal use of Indian cartographic knowledge and met with Indian geographers whenever possible. Nowhere is this more evident than in the reproductions of indigenous charts that appear in his second important work, Cursus Gangæ, which studies the course of the Ganges River to its sources. Tiefenthaler sent his most important cartographic work to the French orientalist and geographer A. H. Anquetil-Duperron who compiled and edited the manuscripts into to important publications, Recherches hist. et géogr. sur l'Inde and an independently issued map Carte général du cours du Gange et du Gagra dressée par les cartes particuliéres du P. Tieffenthaler. Tiefenthaler never returned to Europe and died in Lucknow, India, in 1785. He is buried at the mission cemetery in Agra.