Abstract:
The development of Kiswahili into an international language in the 19th century was contributed
by trade, wars, colonial administration policies, linguistic advantage of this language being
related to Bantu languages in the mainland of E. Africa and religion, among other factors. Most
of these factors have been given prominence, including the role played by Christian missionaries
towards the development of Kiswahili like using Kiswahili in their activities of preaching,
teaching and doing lexicographical research in the key dialects of Kiswahili leading to
compilation of dictionaries. This helped a lot in the spread of Kiswahili in the interior.
However, the role of Islam, which is arguably older than Christianity in E. Africa, has not been
given much coverage. Therefore, this paper intends to highlight how historical interaction
between the Swahili people and Islam contributed to the expansion of Kiswahili from the coast,
therefore enabling this language to establish a stronghold in the interior of E. Africa. The
subject has been approached from a diachronic perspective to expound on the nature of
interactions, their consequences and contribution to the development of Kiswahili.
