De Morgan has said there are signs which show that the Armenians, as their other Aryan relatives, were nature worshipers and that this faith in time was later changed to the worship of national gods, of which many were the equivalents of the gods in the Roman, Greek and Persian cultures. The main proto-Armenian (Aryan) god was Ar, the god of Sun, Fire and Revival. The Armenian hypothesis of Indo-European origins connects the name with the "Ar-" Armenian root meaning light, sun, fire found in Arev (Sun), Arpi (Light of heaven), Ararich (God or Creator), Ararat (place of Arar), Aryan, Arta etc. According to the researchers, the name of Ardini religious center of ancient Urartu also related to the god Ar-Arda. The cult of Ar appear in Armenian Highland during 5-3th millennium BC and had common Indo-European recognition: Ares (Greek), Ahuramazd (Persian) Ertag (German), Ram (Indian), Yar-Yarilo (Slavonic) etc. After adoption of Christianity the cult of Ar was also evident in Armenia, remembered in the national myth, poetry, art and architecture.