Huge rivers descend out of the vast mountain range surrounding Mount Sumeru in the southwest of the world. These rivers flow southward to the sea, and ancient civilizations have sprung up around these rivers, organizing their lives around their cycles of flooding and receding. Broadly, these people are known as the Agama, which is also the name of the language most commonly spoken in the Riverlands.
The people of the Riverlands believe they are the cradle of civilization, while of course the people of the Middle Kingdom disagree. The two peoples certainly look different, and broadly refer to each other as yellow people (the Han) and red people (the Agama).
Agama broadly correlates to the cultures of the Indus river valley.