 The traditional basis of life was challenged by these and other changes, affecting also the other major ethnic groups of the area, such as the Ezhavas and the Syrian Christians.The following Vedic recensions are attested among them.The ancient Vedic ritual of Agnicayana (the altar of fire), which spans a 12-day period and which Frits Staal and Robert Gardner claim to be one of the oldest known rituals, was maintained by Nambudiri Brahmins until at least 1975.