Swahili was born as a language of communication between the Arab merchants, from Oman, and the local Bantu population. That was in Zanzibar, which was an Arabia

Swahili was born as a language of communication between the Arab merchants, from Oman, and the local Bantu population. That was in Zanzibar, which was an Arabian merchant outpost, much safer than the African mainland. So it has a Bantu grammar substrate and lots of Arabic loanwords.