The Tonga never formed a single political unit. Today they are an ethnic group united by common language and in opposition to other Zambian ethnic groups, with whom they compete. The Tonga speak dialects of ciTonga, a Central Bantu language, along with other languages of central and northern Zambia and adjacent regions in Zaire. It was committed to writing by missionaries in the early twentieth century and today has a minute literature, but Tonga writers prefer to write in English, the official language of Zambia. The Central Plateau dialect is becoming the standard used in schools and for broadcasting.