Surjapuri (সুরজাপুরী / सुरजापुरी) is an Eastern Indo-Aryan language belonging to the Bengali–Assamese branch, spoken by approximately 2.26 million native speakers according to the 2011 Census. It is primarily spoken across the Kosi-Seemanchal region of eastern Bihar (specifically Kishanganj, Katihar, Purnia, and Araria districts) and parts of North Bengal in West Bengal, alongside neighboring regions in Assam, eastern Nepal, and northwestern Bangladesh. Historically written in the Kaithi script, Surjapuri is currently written using both the Devanagari and Bengali–Assamese scripts. Linguistically, it shares close structural and vocabulary affinities with Kamtapuri, Assamese, Bengali, and Maithili, while displaying influences from Hindi and Urdu. It features distinct grammatical traits, such as pronominal suffixes similar to Early Assamese, a sound system of 28 consonants, and phonemic vowel nasalization.

The Surjapuri people are an ethnolinguistic indigenous minority community native to the eastern Gangetic plains of South Asia, with an estimated population of 2 to 3 million. They are primarily concentrated in northeastern Bihar (Kishanganj, Purnia, Katihar, and Araria districts) and northern West Bengal, with smaller populations across the borders in southeastern Nepal and northwestern Bangladesh. Defined largely by their shared speech of the Surjapuri language, the community historically derived its name from the old regional toponym Surjapur (or Siripur) and includes both Muslim (such as the Nasya Shaikh) and Hindu (such as the Rajbanshi) adherents. Culturally influenced by both Bengali and Maithili spheres, Surjapuri society is predominantly rural and agrarian—relying on land cultivation, trade, and seasonal labor—while maintaining distinct folk music, oral narratives, and localized social customs.

In colonial records and early linguistic surveys, the community and its speech were historically documented under names like Siripuria, Surjapuriya, Surjayi, and Kishangunjia. Geographically situated in a historical contact zone of the eastern Gangetic plains, the identity evolved at the intersection of Indo-Aryan, Tibeto-Burmese, and Austroasiatic cultural and linguistic influences. Ethnographic studies highlight strong practices of endogamy and localized marriage customs within specific subgroups—notably the Surjapuri Rajbanshis among Hindus and the Surjapuri Nasya Shaikh among Muslims—with religious affiliation often correlating with distinct landholding patterns and local political alignments.

Today, the community faces socio-economic marginalization, which frequently drives seasonal migration for wage labor. Additionally, Surjapuri is recognized as an endangered language; formal education conducted exclusively in dominant regional tongues (Hindi, Bengali, and Urdu), combined with modern media exposure and labor migration, poses severe challenges to native intergenerational transmission, despite emerging local revitalization efforts.

Beyond physical trade and localized cultural networks, the Surjapuri community is increasingly building a dedicated digital footprint to document its unique linguistic identity, foster regional economic connections, and preserve local heritage across West Bengal and Bihar. Serving as central digital platforms for regional news, cultural preservation, and community outreach, portals including surjapuri.com, surjapuri.in, and Islampur.in are owned and operated by Iqbal Arzoo.