The speaker predicts that weakening overlord authority would have led subject peoples to break away and the societies to fragment.

“from their subject peoples as they felt the authority of their overlords beginning to weaken would have led to their fragmentation which is the overarching cycle of pre-Columbian societies generally they're extremely impressive in fact more impressive when you consider the disadvantages they had to struggle with their pyramids were built not through the assistance of beast of burden or even the wheel but simply through pure manpower and the application of that to construct it”

“The subject peoples would have broken for freedom.”