Sites around the coast of Pemba (and Africa in general) are mentioned in literary sources of the time, by travellers to and from the east African coast. Masud, writing in the middle of the 10th century, mentions a place called “Kanbalu in the land of Zanj”, possibly Mkumbu on Pemba. He also mentions the presence of Muslim and non-Muslim residents, as well as the export of ivory, tortoise shells, and other items. How reliably we can assign this to Pemba is uncertain, however it is clear that Pemba had firmly established herself as an important link in the travel and economic chain along the African coast and into the Indian Ocean.
During this millennium throughout the Swahili coast many people converted to Islam. As mentioned in the introductory paragraphs, Pemba is no exception and indeed the most constant feature found on archaeological sites here is a mosque. It has been hypothesised that the speed with which local peoples converted to Islam is due to trade relations with Muslim merchants (a practice seen in other cultures and periods throughout the world, from the New World in the Renaissance to Japan in the early modern era). In addition, the mosques in towns formed a centre of religion which may have encouraged migration and population movement from rural villages to larger townships.
Following the abandonment of Tumbe and moving into the medieval era as it is known in Europe, Pemba saw the establishment of the city of Chwaka, slightly south of Tumbe. A stone town, archaeological surveys indicate that Chwaka began life as a small settlement before growing into a large, densely populated town. Population patterns from the surrounding area indicate that as Chwaka grew the nearby smaller settlements became less populated, thus indicating a migration of the rural populace into the towns. This may be due to the appeal of a cohesive religious community following the mass adoption of Islam, as discussed above. The town of Chwaka itself already housed two standing mosques before archaeological investigation took place; one of which was a large, congregational mosque and the other a smaller, honorific mosque built to honour a former ruler of the town.
Archaeological investigations on the site revealed more and more important structures, eventually totalling four mosques, ten stone tombs, and a stone dwelling displaying a date range of around 500 years between construction. Other homes were found, although these were constructed of earthen materials such as daub rather than stone.
Examination of the mosques indicated they were all built at different times. The first coincides with the date of the site’s first occupation in the eleventh century, and the second appears to haven not been built until the thirteenth. In the following century, the first mosque was demolished and replaced by the third mosque on the same site; this third mosque was far larger and much more elegant, with decorative vaulted ceilings of surprising sophistication given the size of Chwaka at the time. The final mosque was built in the fifteenth century and is much smaller than the rest. The dedication to building and improving upon the mosques suggests the investment of the community, again lending credence to the theory of religious appeal during this period of history.
The constant improvements to the mosques may also suggest a different theory; with the small number of stone homes indicating a minor mercantile elite class present in the settlement, the large number of stone tombs combined with regular mosque enhancements could suggest the site played home to a larger religious elite population. Either way, we cannot be certain. While the mosques have been damaged and the stone tombs are all in different stages of disarray, there is one excellent example of a Swahili pillar tomb.