Satras (Assamese: সত্ৰ) are institutional centers associated with the Ekasarana tradition of Vaishnavism, particularly in the Indian state of Assam and neighboring regions. Numbering in the hundreds, these centers are generally independent of each other and under the control of individual adhikaras (or satradhikars), though they can be grouped into four different Sanghatis (orders).
These centers, in the minimum, maintain a prayer house (Namghar, or Kirtan-ghar), initiate lay people into the Ekasarana tradition and include them as disciples of the Satra from whom taxes and other religious duties are extracted. The Satras started in the 16th century, grew rapidly in the 17th century and patronage extended to them by first the Koch kingdom and later the Ahom kingdom was crucial in the spread the Ekasarana religion. Many of the larger Satras house hundreds of celibate and non-celibate bhakats (monks), hold vast lands and are repositories of religious and cultural relics and artifacts. The Satras extend control over their lay disciples via village Namghars. Satras in which the principal preceptors lived, or which preserve some of their relics are also called thaans.
The satras are established by Assamese Vaishnavite monasteries for religious practices at the initiative of the Ahom Kings of Assam in the middle of the 17th century to propagate neo Vaishnavism.Sankaradeva is said to have established his first Satra at Bardowa, his birthplace, and then in different places of Assam.
In the 20th century the authority and orthodoxy of the Satras was challenged by reform movements, most notable under the Sankar Sangha. The Satras coordinate some of their activities via the Asam Satra Mahasabha, an umbrella organization of all the Satras. According to the Mahasabha's count on its website there is altogether a total of 862 Satras including the satras present in both the states of Assam and West Bengal.
The Satra is generally a four-sided enclosed area with four gateways (karapat). Centrally placed in this enclosure is a rectangular prayer-hall (Namghar or kirtanghar) at the aligned in the east-west direction. On its eastern side there is an 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.