During the late 19th century and lasting until World War II, Africa, as well as many other countries, experienced a period known as New Imperialism, or Neoimperialism. During this time period, the countries of Europe and even the United States colonized many territories within Africa and other countries with the purpose of gaining new trade markets. Niumi is situated in West Africa along the Gambia river and the Atlantic, making it an ideal location for trade. Due to its situation along the Gambia river, in the 19th century, Niumi became part of the Gambia Colony and Protectorate, which is now a country known as the Gambia or the Republic of the Gambia. During the 19th century, England had primary control over colonization in the Gambia, including Niumi, but as early back as the 16th and 17th centuries, both England and France built trading factories in Niumi. Hence, one political change that took place in the 19th century is that England gained total control over the Gambia. In 1783, a treaty had been signed known as the Peace of Paris, giving France of a portion of the Gambia known as Albreda, but by 1889, France signed another treaty yielding all of The Gambia to England, making the Gambia become known as a British Crown Colony.
Niumi, as part of the Gambia, was especially colonized to export its raw materials, such as copper, cotton, rubber, palm oil, cocoa, diamonds, tea, and tin. The increase in trade also brought about an industrial revolution, which of course increased the areas' capital and even brought new developments to the area to accommodate the rise in population. However, with the greater need to mine and harvest more raw materials also came the greater need to have workers, leading to the natives of the area being exploited as cheap laborers ("Reading 2: The New Imperialism in Africa"). Hence, the New Imperialism age affected economic changes in Niumi, as well as other parts of Africa by creating more wealth, but it also created an unequal distribution of that wealth. Since the British Empire exploited the African citizens for their cheap labor and their resources, the British citizens obtained the wealth, while the African citizens continued to suffer.