The Terai area of ​​5 to 7 km wide belt is wide in Bihar.

• A. West Champaran-Sitamarhi-Araria-Kishanganj
• B. West Champaran-Chhapra-Darbhanga-Kishanganj
• C. Sitamarhi-Supaul-Araria-Purnia
• D. Sitamarhi-Madhubani-Madhepura-Purnia