What is the setting in "The Negro Speaks of Rivers"?

Langston Hughes's poem "The Negro Speaks of Rivers" has a universal setting. In the poem, the narrator travels through time and space. The poem begins in the Euphrates, which was, along with the Tigris, the river that bathed ancient Mesopotamia. The narrator also speaks of the Congo, in Africa, and the Nile, which flowed alongside the pyramids in ancient Egypt. The narrator also speaks of the Mississippi, which flows through the United States, and refers to the time of the American Civil War, when Lincoln was President.
By evoking so many places, which date back to ancient times, the narrator is emphasizing the idea that the American Negro has an long and storied past. His or her ancestry goes back to the most ancient civilizations of the Middle East and Africa, and then his or her ancestors were brought, forcibly through slavery, to the New World. The extent of the Negro's experience in time and place gives the Negro a sense of soulfulness that the narrator highlights in the line "My soul has grown deep like the rivers."