[lumost]

I suspect that the motivating factor is lack of deployable human capital. In a large centralized society, there may always people to deploy at the problem. The more people you deploy at the problem, the more time the people at the top spend thinking about people issues and the bureaucracy that comes with that. The bottleneck usually happens when the people at the top become so focused on bureaucracy/politics/corruption that nothing really gets done.

Fragmented societies are less prone to bureaucracy, and more prone to not having enough people available to solve a problem. These factors absolutely help innovation.

[qwytw]

> Fragmented societies are less prone to bureaucracy, and more prone to not having enough people available to solve a problem.

Competition probably also played a part. If the emperor in China or Ancient Rome decided to ban or restrict certain fields/groups/ideas you were pretty screwed, innovation likely stopped, most progress was lost and the next generations had to start from scratch. In Europe you could just move to the next state or city. Same applies to major invasions and societal collapses, e.g. the Byzantine scholars fleeing to Italy during/after the Turkish invasions.