Mairwa is a Sub-District (Tehsil/Block/Mandal) in the Siwan District of Bihar. As par Census 2011 information the sub-district code of Mairwa is 01240. There are about 19 sub-districts in Siwan and Mairwa is one of them. Andar, Barharia, Basantpur, Bhagwanpur Hat, Darauli, Daraundha, Goriakothi, Guthani, Hasanpura, Hussainganj, Lakri Nabiganj, Maharajganj, Nautan, Pachrukhi, Raghunathpur, Siswan, Siwan, Ziradei etc. are other sub-districts in Siwan.There are about 53 villages in Mairwa sub-district, which you can browse from villages list.