the Angkola-Mandailing lands may have been prompted by 8th-century Srivijayan demand for camphor. The Karo marga or tribe Sembiring "black one" is believed to originate from their ties with Tamil traders, with specific Sembiring sub-marga, namely Brahmana, Colia, Pandia, Depari, Meliala, Muham, Pelawi, and Tekan all of Indian origin. Tamil influence on Karo religious practices are also noted, with the pekualuh secondary cremation ritual being specific to the Karo and Dairi people. Moreover the Pustaka Kembaren, an origin story of the Sembiring Kembaren suggests linkages with Pagarruyung in Minangkabau Highlands. From the 16th century onward, Aceh increased the production of pepper, an important export commodity, in exchange for rice, which grew well in the Batak wetlands. Batak people in different areas cultivated either sawah (wet rice fields) or ladang (dry rice), and the Toba Batak, most expert in agriculture, must have migrated to meet demand in new areas. The increasing importance of rice had religious significance, which increased the power of the Batak high priests, who had responsibility for ensuring agricultural success. Language The Batak speak a variety of closely related languages, all members of the Austronesian language family. There are two major branches, a northern branch comprising the Pakpak-Dairi, Alas-Kluet and Karo languages, which are similar to each other, and a distinct southern branch, comprising three mutually intelligible dialects: Toba, Angkola and Mandailing. Simalungun is an early offspring of the southern branch. Some Simalungun dialects can be understood by speakers of Batak Karo, whereas other dialects of Simalungun can be understood by speakers of Toba. This is due to the existence of a linguistic continuum that often blurs the lines between the Batak dialects. Batak dialect still influences the dialects in Medan city today. The Batak possess their own script known as the Surat Batak. The writing has chiefly ceremonial importance within traditional religious ceremonies, and was subject to little change for this reason. It is likely that the Batak people originally received their writing system from southern Sumatra. Contribution to modern Malay and Indonesian literature In the broader context of national language, the modern Batak authors are well-known as the outstanding Malay-speaking writers that shape modern Malay into the national concept of Bahasa Indonesia (Indonesian language) and its literary canon. Merari Siregar (1896–1941) is the author of Azab dan Sengsara (Pain and Suffering, 1920), the first novel written in Indonesian. Muhammad Kasim Dalimunte (born 1886) is the author