Most of the people who live around Lake Toba are ethnically Bataks. Traditional Batak houses are noted for their distinctive roofs (which curve upwards at each end, as a boat’s hull does) and their colorful decor. Batak is a collective term used to identify a number of ethnic groups found in the highlands of North Sumatra, Indonesia. Their heartland lies to the west of Medan centred on Lake Toba. In fact the “Batak” include several groups with distinct, albeit related, languages and customs (adat). While the term is used to include the Toba, Karo, Pakpak-Dairi, Simalungun, Angkola and Mandailing. Occasionally it is also used to include the Alas-Kluet people of Central/Southern Aceh, but usually only as relates to language groups.