additional independent structure called the Manikut (jewel-house), the sanctum santorum, in which the asana, a wooden tetradehral structure with four carved lions), is placed containing the main object of worship (usually a copy of the Bhagavat Purana in manuscript or an idol). The namghar is surrounded by four straight rows of huts, called hati, in which monks (bhakats) reside. The adhikara and other high officers of the Satra reside in the eastern hatis. All structures were originally temporary, made with wood, bamboo and covered over with thatch; brick and mortar found use after the 18th century. Monks, called bhakats, live in satras under a satradhikar or Mahanta. In some orders of the religion, the bhakats are celibate (kewalia bhakat). The satradhikar may not always be of high birth, it is recorded in many instance the satradikars belonging to tribal or lower caste origin. For eg, Mathuradasa Ata, the first satradhikar of Barpeta was from the Candal community, Narayanadasa Ata, a disciple of Sankardev was from the weaver community (Tanti) similarly Sesa, Katani, Budhbari, Chahila satras were held by Kaibartas although they claim to be of Kayastha origin. The satras are not merely religious institutions but play cultural and historical roles in society. A dance form that was initiated by Srimanta Sankardeva and later developed within the sattras, and thus called Sattriya, is one of the eight classical dance forms in India. Origin and evolution The name satra originates in the Bhagavata Purana in Sanskrit (sattra), and is used in the sense of an assembly of devotees. During Sankardev's lifetime, the devotees assembled in the open, under trees. Though temporary prayer houses were built, the tradition of devotees living in the premises did not happen during Sankardev's lifetime. The first mention of the hati is found in the context of the Patbausi Satra of Damodardev. Madhavdev built the Barpeta Satra, and laid down the system of daily prayer service and initiated the system of religious tithes. Vamsigopaldev was instrumental in establishing Satras in eastern Assam. The last quarter of the 16th century saw the satras divide into four different sects (also called samhati)—Brahmasamhati, Purusasamhati, Nikasamhati, Kalasamhati. These four sects were firmly established by the early 17th century. Damodaradeva (a brahmin disciple of Sankardev) formed the Brahmasamhati, which represented the brahmanical practices and ritualism. It brought back the caste system to its original form but still adhered to the teachings of namadharma