Thadi or Thadi Viswaspatti is a very old border town and a market place of Nepal in Siraha District bordering Indian town of Laukaha. It is currently part of Bhagwanpur Rural municipality. It is located nearly 370 kilometers or 107 miles east of the capital, Kathmandu. Thadi was part of Tirhut Rulers of Simraungarh. The region was under rule of Karnad Dynasty formed by Nanyadeva Thadi is one of the few towns which is a part of agreed route for Mutual Trade between India and Nepal. Nepal Government has set up a dedicated customs office in the town.

Siraha District, a district in Madhesh Province, is one of the seventy-seven districts of Nepal. It is situated in the Terai belt of Nepal. The district, with Siraha as its district headquarters, covers an area of 1,188 km2 (459 sq mi). It has population of 637,328 according to census of 2011.The District is bordered with Saptari district in the east, Udayapur districting the north, Bihar state of India in the south and Dhanusa district in the west. Majority of the population here is Yadav, Tharus, Sahs(sahukar), Muslims and ethnic minorities with majority population speaking Maithili language and Nepali language.