The various Batak cultures differ in their pre-colonial religious ideas as they do in many other aspects of culture. Information about the old religious ideas of the Mandailing and Angkola in southern Batakland is incomplete, and very little is known about the religion of the Pakpak and Simalungun Batak. For the Toba and Karo on the other hand the evidence in the writings of missionaries and colonial administrators is relatively abundant. Information on the traditional forms of Batak religion is derived mainly from the writings of German and Dutch missionaries who became increasingly concerned with Batak beliefs towards the end of the 19th century.