I've always wondered how it's possible that entire civilizations, which had developed complex technologies and systems, disappeared within just a few decades or centuries. What were the main causes behind these collapses? I'm reading quite a bit on this topic but I can't find a single clear answer.
There's no single answer because rarely does the collapse of a civilization come down to just one cause. What you're reading is right - history isn't linear. Think about the classic Maya: they didn't vanish into thin air, but a combination of prolonged droughts, demographic pressure, internal wars, and deforestation brought them to collapse between 700 and 1000 CE. Same story with the Minoan civilization on Crete or the Late Bronze Age civilization in the Levant. There was always a mix: drastic climate changes, invasions, disease, economy falling apart, internal political conflicts. Sometimes it was decades, sometimes centuries (what one calls "rapid" is relative when we're talking about historical epochs).
The point is that complex civilizations are fragile precisely because they're complex. They depend on trade networks, on specific agricultural systems, on delicate political balances. If two or three pillars collapse at the same time, the domino effect is swift. The elite stop maintaining infrastructure, the population disperses, written knowledge is lost or no longer passed down. It's not that everyone died: often people simply abandoned the cities and went back to living in a more scattered, less complex way. Their successors were themselves, just in a very different form of society.
The reason you don't find a single answer is that one doesn't exist. Reading multiple sources is the right choice because each one shows you a piece of the puzzle. The key is understanding that "collapse" is never just one thing: it's always a perfect storm of environmental, demographic, political, and economic factors converging.
It's not that they disappeared so quickly, it's that we often tell history badly! A civilization almost always collapsed from a combination of factors - famines, wars, epidemics, climate change, internal corruption - not from a single thing, and the process could take generations even though it seems instant to us when we read two chapters of a book.
The thing is, historical sources are fragmentary, so we see like the peak of a civilization and then silence, and our brain fills in the gaps by thinking everything crashed overnight, when actually people kept living and adapting, just on a smaller scale and without as much political centralization.
Log into answer.
