stylistic:style_transfer
Before 1498

The presence of microliths suggests that Zanzibar has been home to humans for at least 20,000 years, which was the beginning of the Later Stone Age.

A Greco-Roman text between the 1st and 3rd centuries, the Periplus of the Erythraean Sea, mentioned the island of Menuthias (Ancient Greek: Μενουθιάς), which is probably Unguja.

At the outset of the first millennium, both Zanzibar and the nearby coast were settled by Bantu speakers. Archaeological finds at Fukuchani, on the northwest coast of Zanzibar, indicate a settled agricultural and fishing community from the 6th century at the latest. The considerable amount of daub found indicates timber buildings, and shell beads, bead grinders, and iron slag have been found at the site. There is evidence of limited engagement in long-distance trade: a small amount of imported pottery has been found, less than 1% of total pottery finds, mostly from the Gulf and dated to the 5th to 8th century. The similarity to contemporary sites such as Mkokotoni and Dar es Salaam indicates a unified group of communities that developed into the first center of coastal maritime culture. The coastal towns appear to have been engaged in Indian Ocean and inland African trade at this early period. Trade rapidly increased in importance and quantity beginning in the mid-8th century and by the close of the 10th century, Zanzibar was one of the central Swahili trading towns.

Excavations at nearby Pemba Island, but especially at Shanga in the Lamu Archipelago, provide the clearest picture of architectural development. Houses were originally built with timber (circa 1050) and later in mud with coral walls (circa 1150). The houses were continually rebuilt with more permanent materials. By the 13th century, houses were built with stone, and bonded with mud, and the 14th century saw the use of lime to bond stone. Only the wealthier patricians would have had stone- and lime-built houses, and the strength of the materials allowed for flat roofs. By contrast, the majority of the population lived in single-story thatched houses similar to those of the 11th and 12th centuries. According to John Middleton and Mark Horton, the architectural style of these stone houses have no Arab or Persian elements, and should be viewed as an entirely indigenous development of local vernacular architecture. While much of Zanzibar Town's architecture was rebuilt during Omani rule, nearby sites elucidate the general development of Swahili and Zanzibari architecture before the 15th century.

From the 9th century, Swahili merchants on Zanzibar operated as brokers for long-distance traders from both the hinterland and Indian Ocean world. Persian, Indian, and Arab traders frequented Zanzibar to acquire East African goods like gold, ivory, and ambergris and then shipped them overseas to Asia. Similarly, caravan traders from the African Great Lakes and Zambezian Region came to the coast to trade for imported goods, especially Indian cloth. Before the Portuguese arrival, the southern towns of Unguja Ukuu and Kizimkazi and the northern town of Tumbatu were the dominant centres of exchange. Zanzibar was just one of the many autonomous city-states that dotted the East African coast. These towns grew in wealth as the Swahili people served as intermediaries and facilitators to merchants and traders. This interaction between Central African and Indian Ocean cultures contributed in part to the evolution of the Swahili culture, which developed an Arabic-script literary tradition. Although a Bantu language, the Swahili language as a consequence today includes some borrowed elements, particularly loanwords from Arabic, though this was mostly a 19th-century phenomenon with the growth of Omani hegemony. Many foreign traders from Africa and Asia married into wealthy patrician families on Zanzibar. Asian men in particular, who resided on the coast for up to six months because of the prevailing monsoon wind patterns, married East African women. Since almost all the Asian traders were Muslims, their children inherited their paternal ethnic identity, though East African matrilineal traditions remained key.