[2] The vast majority of what is known by linguists about Jarawan languages is gleaned from wordlists, many of which were compiled very early in the 20th century, and contain anywhere from a couple dozen to approximately 400 words, and occasionally a few phrases or simple sentences.

The Jarawan lexicon is heavily influenced by Chadic languages, and particularly Hausa, due to contact.

The prefixes are no longer productive, and there is no related system of agreement or concord, as found in modern day Bantu languages.

Gowers (1907) has six wordlists of Jarawan Bantu (Bomborawa, Bankalawa, Gubawa, Jaku, Jarawa, and Wurkunawa) included in his survey of the largely Chadic languages of the Bauchi area.

Strümpell (1922) and Baudelaire (1944) are the only records of Nagumi, based around Natsari, SE of Garoua in northern Cameroun.

In 2016, Adelberger & Kleinewillinghöfer published a history sketch and lexicon of Kulung, as compiled by the missionary Ira McBride.

According to Blench (2006): "Maddieson & Williamson (1975) represents the first attempt to synthesise this data on the position of these languages.

Ulrich Kleinewillinghöfer has made available a comparative wordlist of six Jarawan Bantu lects; Zaambo (Dukta), Bwazza, Mbula, Bile, Duguri and Kulung, collected in the early 1990s as part of the SFB 268."

Work begun in 2018 by Green at Syracuse University has focused on languages of the "Jar" cluster, and particularly on description and documentation of Mbat (Bada) and Duguri.