15,000,000 in Tanzania (2012), increasing. Population total all countries: 15,457,390. L2 users: Probably over 80% of rural people are L2 users; they use the local language for most activities, but Swahili [swh] with outsiders.
Formerly Zanzibar, coastal areas. Now widespread.
1 (National). De facto national language.
Mambrui (Malindi), Mgao (Kimgao), Mrima (Mtang’ata), Pemba, Unguja (Kiunguja, Zanzibar). Lexical similarity: Bajun dialect 85% with the Amu dialect, 78% with the Mvita dialect, 72% with the Mrima dialect; Mvita dialect 86% with Amu, 79% with Mrima; Mrima dialect 79% with Amu. A member of macrolanguage Swahili [swa].
It is also common for people of numerous ethnic groups to speak Swahili as L1, especially in urban and very mixed areas. All domains. All ages. Positive attitudes.
Muslim, Christian, traditional religion.