According to http:///emuseum/cultural/oldworld/africa/ , the Bantu are an ancient group of people from Africa, whose origins are unclear. Some of the people from West Africa traversed from the Congo or Niger Delta Basin to become the main inhabitants of East and South Africa. They migrated slowly, such as in small groups and in the process of traveling they became known no longer as West Africans, but rather the Bantu, which translates as “The People.” They migrated within the years of 1000-1800 AD. There are several hypothesis as to why the Bantu moved; one being that the population simply became too large and thusly forced some to move and practice agriculture; another is that they were searching for fertile land. When the Bantu met hostile tribes they used iron weapons, which they developed around 400 . When they reached their destination, some of the Bantu in South Africa married the pre-existing people there, who were known as the Khoikhoi and the San people. During their transition from nomads to settlers they adapted farming and keeping livestock, but those who wished to remain hunters and gatherers were forced off the farming land and into the desert. Many people did not migrate with the Bantu, such as the people of modern Mali, which are dated to have been there by 250 . The Bantu helped develop the land to which they moved by introduce new foods, such as millet and sorghum. It has also been speculated that they introduced iron smelting and iron tools. They have grown to about 60 million linguistically related people.
Past ancient times, according to http:///co/bantu/ , before 1000 . Persian and Arab traders had already started to trade with east Africans. After having made contact, many refugees fled here to avoid the chaos in Arabia after Muhammad’s death, which occurred in the 7th century. Because of Arabian immigrants mixing with the Bantu, the Swahili people were born. During the next seven centuries the Swahili people worked with the Bantu and spread their communication deeper into Africa to new tribes.
Then came the colonial period, which brought the Portuguese. By the 15th century the Portuguese found a modern economy and advanced economy, so much so that some even said that it rivaled Europe. Once the Portuguese gained control the local economic networks were broken down.
After the Portuguese were overthrown by the Omani Arabs in 1730, the Swahili were given some rights back, but the Omani Arab rule proved to be disastrous for the inland African tribes. The Omani Arabs practiced slavery, which was one of their major economic enterprises.
Due to the need for cheap labor in the 18th century the Sultan of Oman, whose name was Sayyid Said, moved his seat of power, in 1840, to Zanzibar, near east Africa’s coast. His territory then expanded from northern Mozambique to southern Somalia. The Africans in these areas were abducted into the slave trade. Tanzania was exceptionally affected by the slave trade.
The people who were responsible for abducting slaves were agents of the Sultanate of Zanzibar and some African tribes. The main source of slaves were from raids and prisoners. Some written accounts tell of slave traders marching the slaves 400 miles to the coastal city of Kilwa Kivinje.
Writing , developed first by people in Sumer , is considered a hallmark of civilization and "appears to accompany the rise of complex administrative bureaucracies or the conquest state".  Traders and bureaucrats relied on writing to keep accurate records. Like money, writing was necessitated by the size of the population of a city and the complexity of its commerce among people who are not all personally acquainted with each other. However, writing is not always necessary for civilization, as shown the Inca civilization of the Andes, which did not use writing at all except from a complex recording system consisting of cords and nodes instead: the "Quipus", whose still functioned as a civilized society.