What facilitated the spread of Islam in East Africa?

Factors that facilitated the spread of Islam in East Africa?

1. Proximity of East Africa to Arabia.
2. Existence of muslim city states which harboured the arabs
3. The roles of the Somalis – closeness to Saudi Arabia.
4. The existence of trade goods in the interior of East Africa.
5. Intermarriage between Arabs and the local people.
6. The chiefs – hospitality of these chiefs to the arabs
7. Missionary workers – from Tanganyika