[rgergerge3]

I am not sure about Lingala but Swahili absolutely spread through coercion in colonial times and post independence. In Tanzania the Germans and later the British heavily promoted Swahili as a lingua franca.

Nowadays Swahili is the first language of most Tanzanians but in the past it was mainly limited to coastal areas formerly controlled by the Sultanate of Oman. The government of Tanzania promotes Swahili to this day, and many native languages in the interior of the country are declining.

[AnAfrican]

Yes but it did and does spread beyond Tanzania. Lingala probably did have some government help too in Mobutu’s era but still.