The Batak of northern Sumatra are grouped within the Austronesian language family, although there are numerous ethnic groups, dialects, kinship systems and religious customs. Each group has its own alphabet, perhaps via the ancient Javanese Kawi script rather than directly from South Asia. The ‘bark’ books were traditionally made from the bast of the alim tree (Aquilaria malaccensis). This is cut into strips and folded concertina fashion, with ink applied to engraved lines of writing. The pustaha record various types of knowledge, including cures for illness, massage, the production of amulets, offensive magic and shooting. There are also calendars used to determine auspicious days for journeys, planting, marriage, house-building or other social activities. (Text by John T. Carpenter and Yoshiko Yasumura, from the exhibition catalogue: Objects of instruction : treasures of the School of Oriental and African Studies, Anna Contadini, Editor. London : SOAS, University of London, 2007.)