How did the triangle trade work?

On the first leg of their three-part journey, often called the Triangular Trade, European ships brought manufactured goods, weapons, even liquor to Africa in exchange for slaves; on the second, they transported African men, women, and children to the Americas to serve as slaves.

because other regions has other things that egypt doesnt have.

it foreshadows the theme of the paragraph and hints the topic that will be discussed in the paragraph!