There are about 170,000 speakers of the Malawi language called Tonga, also called Western Nyasa.
The language is called chiTonga. The 'chi' means 'the language of the', like 'ki' in kiSwahili or 'se' in seTswana.
The Tonga language of Malawi is described as "similar" to Tumbuka and Turner's dictionary  lists only those words which differ from the Tumbuka, with the added comment that "the Tonga folk, being rapid speakers, slur or elide the final syllable of many words, e.g. kulira becomes kuliya, kukura becomes kukuwa, kutoa becomes kuto’."