The Swahili are unique Bantu inhabitants of the East African Coast come mainly from Kenya, Tanzania, and Mozambique. They are united by culture and the mother tongue of Kiswahili, a Bantu language. This also extends to Arab, Persian, and other migrants who reached the coast approximately in the early 7th-8th century. They mixed with the local people there, providing considerable cultural infusion and words borrowed from Arabic and Persian. Archaeologist, Felix Chami notes the presence of Bantu settlements straddling the East African coast as early as the beginning of the 1st millennium. They evolved gradually from the 6th century onward to accommodate for an increase in trade (mainly with Arab merchants), population growth, and further centralized urbanization; developing into what would later become known as the Swahili City-States.
Around 90 million people speak the Swahili language and it is Tanzania’s official language. However, those who live elsewhere in East Africa also speak the official languages of their respective countries: English in Kenya, Portuguese in Mozambique, and French in Comoros. Note that only a small fraction of those who use Swahili are first language speakers and even fewer are ethnic Swahilis. This point is often obscured by the Swahili linguistic tradition in which those who speak the language are often called Swahili (Waswahili) regardless of their actual ethnic origins. In other words, the term ‘Swahili’ can mean ‘those who speak Swahili’ or it can mean ‘ethnic Swahili people’.
Islam established its presence in the East African coast from around 1012 AD, when the traders from the Persian Gulf and the Arabian Peninsula continued to journey to these parts during monsoon seasons and to interact with the local people through trade, intermarriage and an exchange of ideas. Because of this interaction, most of the Swahili today are Muslim. The unifying force of Islam consolidated into an amalgam of otherwise different ethnicities and provided an enduring common identity for many of the people in coastal East Africa. The Swahili follow a very strict and orthodox form of Islam.
As on many other continents, Christianity has a presence in many of the Waswahili people.
For centuries the Swahili depended greatly on trade from the Indian Ocean. The Swahili have played a vital role as middle-man between east, central, South Africa and the outside world. Trade contacts have been noted as early as 100 A.D. by early Roman writers who visited the East African coast in the first century. Trade routes extended across Tanzania into modern day Democratic Republic of the Congo, along which goods were brought to the coast and were sold to Arab, Indian, and Portuguese traders and even reached as far as China and India. Materials attributed to this network of trade were also found at Great Zimbabwe. During the apogee of the middle ages, ivory and slaves became a substantial source of revenue. Many slaves sold in Zanzibar ended up in Brazil, which was then a Portuguese colony. Swahili fishermen of today still rely on the ocean to supply their primary source of income. Fish is sold to their inland neighbors in exchange for products of the interior.