This sounds not very thorough. The cultural movement vector accelerators are quite visible. The mediterranen coas allowed several cultures to create trade netwo

This sounds not very thorough. The cultural movement vector accelerators are quite visible. The mediterranen coas allowed several cultures to create trade networks. And the eastern steppes allowed military raid alliances to put military evolutionary pressure on kingdom and empires. The self sufficient battle sponge like structure of central Europe promoted constant cultural competition (unlike nowadays). The model they used must be flawed.