The following were the reasons for the coming of Arabs to the coast of east africa
TRADE: It is noted that since time in the memory there existed commercial relationship between Arabs and the people of E. African coast. At the coast, there existed tradable items like gold, ivory, agricultural parts etc which were got from the interior of E. Africa to the coast and they were exchanged with items like clothes, glass wear, guns etc. Therefore the major reason why the Arabs came to the coast was to trade.
SEEK FOR REFUGE: It is on record that during fighting wars in Arabia, many Muslims left their homeland and got shelter on the E. African coast. It should be noted that during these civil wars and conflicts, some Arabs and Persians found it impossible to stay at home therefore they decided to migrate to the E. African coast to safety their lives.
There was need to acquire new lands in form of colonies. It is reported that some Arabs came to acquire colonies on the E. African coast and practice the Islamic law on the people of East Africa. When they arrived, they really established dynasties and they spread Islam as well.
Presence of monsoon winds; The movement of Arabs from their homeland to E. African coast was facilitated by the presence of monsoon winds blew 2 periods in the year ie from Middle East to E. Africa and from E. Africa to middle.
The good favourable climatic conditions at the coast: These conditions led to the coming of the Arabs who settled on the E. African coast e.g. Saidi Seyyid moved his capital from Oman to Zanzibar due to good climate at the coast which favoured Agric.
Need to spread Islam. Some few Arabs wanted to spread Islam despite the fact that the majority came at the coast for other things. They did this put in practice the command of Allah which is to spread his religion.
Some of the Arabs to E. African coast because of love for adventure e.g. Ibin Batuuta came to see the nature of the E. African coast and its physically features.
The hospitable nature of the people of East Africa. People of East Africa were so welcoming the Arabs a situation that attracted many Arabs to come and settle permanently at the coast.
Bandwagon effect: Some Arabs came to the coast because they saw their friends coming.