The development and evolution of the Swahili language was significant in the respect that it is an example of the changes that were necessary for the Indian Ocean economy to survive. The coastal areas of East Africa saw influence from several fronts, notably Portuguese, Arabic and Persian influence especially in terms of the development of the Swahili language.
The Indian Ocean economy at these early-modern times was seeing high levels of trade, immigration and strife between controlling powers throughout the Indian Ocean and from Europe. The Swahili coast of East Africa had many ports competing to be the primary
exports for several goods including ivory, ambergris, beeswax, tree resin and wood. The port or Kilwa also exported gold amongst other things. The evolution of trade brought with it the desire for foreign demand of the products available from these coastal countries.
Improvements in ship design coupled with navigational accuracy that came about at this time enabled more traders to seek out the African coast. The Portuguese were a huge influence in a majority of the coast of East Africa, though it struggled to keep control of certain ports. Portugal, in addition to the East African coas,t had ports in India and areas further East. This cross culture brought about a need for more uniform means of communication.
Further, Arab and Muslims who settled in the east African coastal area played a large role in the development of the Swahili language and culture as well. Again, there was intermarriage and a cross culture that developed that required more uniform means of communication. This mixed population that developed over these times also had a large influence on Swahili culture.
At a time when trade was growing so rapidly and intermarriage and immigration was booming, it was inevitable that there would be cross over between languages and culture. In fact, the development of such a strong industrialized economy could not have been nearly successful without these means of communication.