 Similar concepts exist in many Indo-European cultures and the names can in addition be derived from an identical root word "*".This is why some scholars take the position that the concepts in the Indo-European daughter cultures have a common ancestor in the Proto-Indo-European culture.In contrast Hermann Oldenberg (1894) surmised that the concept of "Ṛta" originally arose in the Indo-Aryan period from a consideration of the natural order of the world and of the occurrences taking place within it as doing so with a kind of causal necessity.