By the beginning of the study period, Central Africa (Cameroon, Gabon, both Congos, Central African Republic, Angola, Zambia, Malawi, Mozambique) had already been settled by Bantu language-speaking, iron-working agriculturists. Indeed, Cameroon was the Bantus' point of origin in roughly BGW 1000. "Central Africa" really encompasses two geographic regions:
Of the Congo basin we have next to no information from the era prior to European colonization.. We have little good information about Angola and the interior prior to the arrival of the Portuguese in both Angola and Mozambique. In the savannahs, kingdoms engaged in extensive trade, and people were rather mobile. Thus, if your ancestors were in any one spot in CE 1900, it is safe to assume that their ancestors came from ever larger areas in earlier periods.
Fifth to Fifteenth centuries - Swahili culture: Trade between the Middle East and communities on the East African coast was in place since before CE 1. With the rise of the Umayyad Caliphate, this trade increased, with Arab and Iranian traders settling in town like Mogadishu, Lamu, Mombasa, Pemba, and Zanzibar extending south to Mozambique, marrying locals, and coordinating trade with the relatives back home. The ultimate result was the rise of Swahili culture - Islamic in outlook but primarily African in personnel. The Kiswahili language reflects their character - Bantu in essence but with many Arabic words. Nevertheless, if your ancestors lived in the coastal towns of Mozambique in CE 1490, their ancestors probably also lived in Arabia, Iraq, or Iran in earlier periods, also.
The Swahilis both traded with the interior for forest products and raided the interior for non-Muslim captives that formed their labor force and later, became a major export item. Thus, your Swahili ancestors of CE 1490 may also have had ancestors in the interior of Mozambique or Malawi.
Sixteenth century - Portuguese slave trade in Angola: The appearance of the Portuguese in Angola brought about several transformations. The Portuguese tried to set up a system of trade with local suppliers similar to that of the "slave coast" of West Africa. Their local trading partners, the kingdoms of Kongo and Ndongo in northwest and west-central Angola. These kingdoms, were fragile, vulnerable to reprisals, and exerted less control over the countryside, motivating the Portuguese to establish colonies and manage the slave trade themselves. Many early colonists intermarried and assimilated with local populations. Thus, if your ancestors lived in Angola in CE 1800, then probably some of their ancestors lived in Portugal in CE 1490.
The slave, and later ivory trade stimulated the development of more intense long-distance trade networks, linking the interior (eastern Angola, Zambia, southeastern Congo) to the Angolan coast. Thus, if your ancestors lived anywhere in these countries in CE 1800, their ancestors could have been anywhere else in CE 1490.
The Sixteenth Century - Portugal attacks the Swahilis: When the Portuguese developed sea routes to the Indian Ocean, they discovered the rich Swahili trade with the Middle East and sought to coopt it. One by one, Swahili towns fell to their attacks and became hosts to Portuguese garrisons and forts. Thus, your Swahili ancestors of CE 1800 may also have had ancestors in Portugal in CE 1490.
Eighteenth and Nineteenth Centuries - society breaks down: In the East, the Portuguese slave trade intensified into the 19th century. These were mostly taken from inland Mozambique, Malawi, and Zambia and shipped to the French colonies of Mauritius and Reunion, or to Brazil. As the slave trade intensified in the early nineteenth century, East and Central African communities were severely disrupted. Almost as bad was the trade in ivory, in which innocent people were captured by ivory traders for use as porters or held until a ransom of elephant tusks was paid. These disruptions persisted through the 19th century. If your ancestors lived in Mozambique, Malawi, or eastern Zambia in CE 1900, their ancestors could have been from anywhere there or in adjacent parts of east or southern Africa in CE 1800 and CE 1490.
Early nineteenth century - "crushing" and "scattering": The consolidation of the Zulu and Sotho kingdoms of southern Africa resulted in a series of epic migrations alternately called the Mfecane ("crushing") or Difaqane ("scattering") by peoples on the giving or receiving end. These migrations reached central Africa in two episodes:
Late nineteenth century - colonization: The disruptions of the slave and ivory trade were an invitation for Western powers to step in, restore order, and manage the export trade. Thus, Portugal established its colonial authority over Angola and Mozambique by careful exploitation of local conflicts. Zambia and Malawi were administered by Britain, Cameroon by Germany, and the Central African Republic and the Democratic Republic of the Congo by France.
The Republic of the Congo's fate was especially nasty, as it became the personal colony of Belgian King Leopold II who granted concessions to commercial firms for the open plundering of natural resources, especially rubber. A typical routine would be for company agents to demand a quota of rubber from each person in a native village then kill any people who didn't cough it up. It was a tough choice - ignore your gardens and fields and starve or ignore the order to collect rubber and get shot. We don't typically think of the Belgians when we think of history's most notorious genocides, however the Congo lost more people in fifty years than Angola or west Africa did at the height of the slave trade. In 1908, the king ceded his private domain to the government of Belgium, which administered it somewhat better.
And yet, intermarriage between colonists and locals was not completely unheard of. Your family folklore and the evidence of your senses will inform you.