Aja is a Nilo-Saharan language of the Central Sudanic subgroup, spoken in the southern Sudanese province of Bahr el Ghazal and along the Sudanese border in the Central African Republic. Although the tribe considers itself to be Kresh, the language is unintelligible to the Kresh and is halfway between Kresh and Banda. It is near Banda in vocabulary and Kresh in structure. Most members of the tribe are bilingual in Kresh. Alternate names are Adja and Ajja.