The core curriculum set by the National Board of Secondary Education included English, mathematics, and Dzongkha. Although English was used as the language of instruction throughout the junior high and high school system, Dzongkha, and, in southern Bhutan until 1989, Nepali, were compulsory subjects. Students also studied English literature, social studies, history, geography, general science, biology, chemistry, physics, and religion. Curriculum development often has come from external forces, as was the case with historical studies. Most Bhutanese history is based on oral traditions rather than on written histories or administrative records. A project sponsored by UNESCO and the University of London developed a ten-module curriculum, which included four courses on Bhutanese history and culture and six courses on Indian and world history and political ideas. Subjects with an immediate practical application, such as elementary agriculture, animal husbandry, and forestry, also were taught.