Talni is the language of the Tallensi people who live in and around the Tong Hills , and the town of Tongo (10°43′N 0°48′W) in the Upper East Region of Ghana.
The people and their customs are known outside the area because they are the keepers of important traditional shrines and were studied by social anthropologists in colonial times, with publications such as :
Fortes, Meyer 1945. The dynamics of clanship among the Tallensi. London : OUP
Fortes, Meyer 1949. The web of kinship among the Tallensi. London : OUP
Rattray, R.S. 1932. Tribes of the Ashanti hinterland [2 Vols.] Oxford /London : OUP
Nothing has been published specifically on the language and it has not been developed with an orthography and publications., but the above sources contain linguistic data, that of Fortes being quite clear and consistent, though strong on vocabulary of social interest and weak on general terms. Supplemented by my own data this yields quite a good first lexicon for this series, with nearly 1000 words.
Although it has been considered a dialect of the linguistically-different but culturally/politically dominant Farefari language and community to the north (including the ISO 639-3 classification) the arguments for separate language status are presented <Here>.
The Talni dictionary can be downloaded here.
A brief linguistic note on Talni which I prepared in 2015 to accompany the dictionary can be seen here.