Volcanic eruptions can destroy building that store resources, burn trees, kill animals and make land not suitable for farming etc
Religious and ethnical problems.
It was one of the largest empires of the world with many different ethnicities. The problem was to unite people under one rule.
Another problem was communication. It was hard to transfer knowledge and news to all parts of the empire because it was too large.
Natural resource management is a discipline in the management of natural resources<span> such as land, water, soil, plants and animals, with a particular focus on how management affects the quality of life for both present and future generations.Hence sustainable development can be followed where there is a judicial use of the natural resource.</span>
The answer is actually Convection.