The geographical area of Gramthan Rural Municipality is 71.84 sq km. It has a population of 32717 according to census 2011. This rural municipality has seven wards. It was formed by merging six former VDCs. The headquarter of this municipality is situated in Tetariya.
Tharu, Rajbansi, Batar and Sardar people lives in this area. They are known to be Terai origin people. The fertile land of terai makes them more attached to agricultural production for commercial purposes.
The administrative structure under this rural municipality has five departments. Administrative, Planning and Monitoring Department, Infrastructure Development and Environment Management Department, Social and Economic Development Department, Education, Youth and Sports Department, Internal Audit Unit.
The Chairperson and Vice chairperson this rural municipality are Shiva Narayn Majhi and Phul Kumari Chaudhari respectively.