The correct answer is notation or musical notation.
Musical notation is a way of having to write down music in a
way of allowing one to play it and that systems are used and associated by in
in order to use it in writing music.
Bodies of water, specifically rivers.
"To accommodate for lack of dependable rainfall" would be the best option as to why the ancient Chinese organized large groups of people to build and maintain irrigation systems, since when rainfall would not come for long periods of time, the crops would likely die without proper irrigation.
