How did loess influence the development of early Chinese civilizations?

Loess is fine yellow soil that is the result of erosion of granite. The particles in the soil are bigger than clay but smaller than sand. This means that this soil is easy to work with and can hold a lot more water than sand. In the early Chinese civilisations this soil guaranteed a succesfull crop, in the dry conditions typical for inland China. These succesfull crops and therefore stable income of food led to a growing population and the first cities in China.