Bihariganj is located in Northeast India and is part of the Mithila region.

In the 16th century, the main stream of the Koshi River flowed to Bihariganj, named "ha-ha dhar", with a small market approximately 2 kilometers away.

[citation needed] Bihariganj is the central market of its surrounded villages.

It is surrounded by villages like Rajghat, Gangaura, Rajganj, Madhukarchak, Mohanpur, Laxmipur, Belahi, Babhangama, Tulsia, Baijnathpur, Vishanpur, Gamail, Mahikhand, Madhuvan Tintenga, and others.

It is located 41 kilometres (25 mi) southeast from Madhepura, the district headquarters.

Other crops include corn, mango, sugarcane, sunflower, mustard, jack fruits, banana, and seasonal Indian vegetables.