Tswana
4.400.000 speakers
6 language specific characters
ISO 639 code: tsn
diacritics
Tswana is a Bantu language spoken by about 4.4 million people in Bostwana, where it is the national and majority language, Namibia, Zimbabwe and South Africa. The majority of speakers, about 3.6 million, live in South Africa, where the language is officially recognised. Tswana is closely related to Southern and Northern Sotho, and is also known as Beetjuans, Chuana, Coana, Cuana and Sechuana.
There some difference between the Tswana orthographies used in Botswana and South Africa.
source
wikipedia.org, omniglot.com & ethnologue.com
younger brothers
twin brothers