Here's why:
* Trade Routes: From the 8th century onward, Arab traders established important trade routes along the East African coast. This brought them into contact with Bantu-speaking communities in the region.
* Language Influence: The Arabic language had a significant impact on the Bantu languages spoken in the area, leading to the development of Swahili.
* Vocabulary and Grammar: Swahili borrows many words from Arabic, particularly in areas related to trade, religion, and administration. The language also shows Arabic influence in its grammatical structure.
It's important to note that Swahili isn't simply a "mixture" of Arabic and Bantu languages. It's a distinct language with its own unique features and evolution, influenced by various factors including the historical interactions between Arab and Bantu speakers.