By studying ancient civilizations, such as the Greek and Roman empires and the Angkor civilization of Southeast Asia, historians have concluded that these civilizations declined partly because of:

Many historians have concluded that the collapse of these societies is due to environmental destruction for the rapid growth of the populations.

Explanation:

Specifically, many studies have been carried out, and even mathematical models to study the similarities in the causes of collapses and falls of great empires and civilizations such as the Greek, Roman and Angkor among others. With all these studies it has been determined that the main reason for the fall of these empires is directly related to the rapid growth of the population and the slow development of resources (agriculture and resources to survive); what has triggered serious economic and political problems too.