What is an economic system

a system of production

Explanation:

An economic system, or economic order, is a system of production, resource allocation and distribution of goods and services within a society or a given geographic area. ... As such, an economic system is a type of social system. The mode of production is a related concept.

nothing certain is known about what happened, but it seems that the country declined gradually, perhaps due to bad government, or, more likely, due to a series of bad harvests, which resulted in widespread and recurrent famine.