Zanzibar has been inhabited, perhaps not continuously, since the Paleolithic period. A 2005 excavation at Kuumbi Cave in southeastern Zanzibar found heavy duty stone tools that showed occupation of the site at least 22,000 years ago.[1] Archaeological discoveries of a limestone cave used radiocarbon techniques to prove more recent occupation, from around 2800 BC to the year 0 (Chami 2006). Traces of the communities include objects such as glass beads from around the Indian Ocean. It is a suggestion of early trans-oceanic trade networks, although some writers have expressed doubt about this possibility.
No cave sites on Zanzibar have revealed pottery fragments used by early and later Bantu farming and iron-working communities who lived on the islands (Zanzibar, Mafia) during the first millennium AD. On Zanzibar, the evidence for the later farming and iron-working communities dating from the mid-first millennium AD is much stronger and indicates the beginning of urbanism there when settlements were built with mud-timber structures (Juma 2004). This is somewhat earlier than the existing evidence for towns in other parts of the Swahili Coast, given as the 9th century AD. The first permanent residents of Zanzibar seem to have been the ancestors of the Hadimu and Tumbatu, who began arriving from the African Great Lakes mainland around 1000 AD. They had belonged to various Bantu ethnic groups from the mainland, and on Zanzibar they lived in small villages and failed to coalesce to form larger political units. Because they lacked central organization, they were easily subjugated by outsiders. .