Wirth was one of the most controversial prehistorians in Germany. After examining symbols found in rural Frisian folk art, he became convinced that they represented the survival of an ancient script used by a prehistoric Nordic civilisation. This script—Wirth believed—was the world's oldest written language and had been the basis for all other ancient scripts. He also believed that if he could decipher it then he would learn the nature of the ancient religion of the Aryan race. This belief conflicted with established scholarly understandings of the past; by the 1930s, scholars were aware that the world's two oldest scripts were those of Mesopotamia and Egypt, and that northern Europe only developed its own form of literacy, that of the runes, under the influence of Etruscan script between 400 BCE to 50 CE. Attempting to explain the lack of any archaeological or historical evidence for an ancient advanced Nordic civilisation, Wirth claimed that the Aryans had evolved in an Arctic homeland two million years ago, before establishing their advanced society on a land in the North Atlantic which had since sunken into the sea, giving rise to the stories about Atlantis.