Angika is mainly spoken in Anga area which includes Munger, Bhagalpur and Banka districts of Bihar and the Santhal Pargana division of Jharkhand.
Bajjika or Western Maithili is spoken in eastern India and Nepal. It is considered to be a dialect of the Maithili language.[20] Bajjika is spoken in the north-western part of Bihar which mostly spans the modern day Tirhut Division and thus is also referred to as Tirhutiya.
Bhojpuri has several dialects: Southern Bhojpuri, Northern Bhojpuri, Western Bhojpuri, and Nagpuria.
Magahi is spoken in the Magadh region in southern Bihar. Its heartland is Patna, Jehanabad, Nalanda, Gaya, Nawada and Sheikhpura districts, with the centres of Magahi culture being Patna, earlier called Pataliputra, and Gaya.
Khortha language is spoken in far-southern Bihar adjoining Jharkhand, on the Chota Nagpur plateau. Districts where Khortha is spoken include Aurangabad, Gaya, Nawada and Jamui.
Surjapuri is a language variety spoken in Purnia division (Araria, Purnia, Katihar and Kishanganj districts), and adjoining areas of West Bengal, although it has been clubbed under Hindi in the census.
Tharu is spoken by the Tharu people of the Terai region in Nepal and neighboring regions of Uttarakhand, Uttar Pradesh and Bihar in India