The Nambudiri Brahmins were at the top of the ritual caste hierarchy and in that system outranked even the kings. They regarded all Nairs as "Shudra". Below the Nambudiris came the Tamil Brahmins and other later immigrants of the Brahmin "varna". Beyond this, the precise ranking is subject to some difference in opinion. Kodoth has placed the Samantan caste below the Kshatriya rank but above the Nairs, but Gough considers that the Pushpagans and Chakyars, both of which were the highest ranked in the group of temple servants known as Ambalavasis, were ranked between the Brahmins and the Nairs, as were several other members of the Ambalavasi group. She also believes that some Nairs adopted the title of Samantan in order to emphasise their superiority over others in their caste. The unwillingness of the higher "varnas" to engage in what they considered to be the polluting activities of industrial and commercial activity has been cited as a reason for the region's relatively limited economic development.