Final answer:
Ancient river civilizations utilized various systems of trade, such as redistributive economic systems, and shared common diplomatic practices. Examples of these civilizations include those along the Nile, Yellow River, and Tigris River.
Step-by-step explanation:
Ancient river civilizations utilized various systems of trade to facilitate economic exchange. One widely used system was the redistributive economic system. Under this system, agricultural goods were collected as taxes from local farmers and stored in palaces or temples. The goods were then redistributed to urban artisans, merchants, and officials who did not produce food. Another common feature among these civilizations was the presence of elite warriors trained to fight from horse-drawn chariots.
Furthermore, these civilizations employed common diplomatic practices. Official correspondence was often written in Akkadian cuneiform, military alliances were sealed through arranged marriages between royal families, and vassal states paid tribute to more powerful states to avoid military assaults.
Examples of such ancient river civilizations include those along the Nile in Egypt, the Yellow River in China, and the Tigris River in Mesopotamia. These civilizations developed agrarian societies in fertile river valleys and witnessed the growth of specialized artisans and a ruling class focused on wealth and power.