Gog Magog civil war with the west

[Anomalocaris]

actually imperialism also made much of humanity’s progress possible.

Any stable environment will help. Hereditary empires are perhaps the least flexible of the available options.

too prolonged a stable environment discourages progress, periodic instability creates opportunities and demand for progress.  Imperialism is both also a natural outcome of a periodically unstable world, and competing imperialism by several powers is one of the key mechanisms that maintains this periodic instability.