Complex structures break in interesting and unexpected ways. This is applicable to both sea shells* and civilizations. Some results are prettier than others.
Two books I greatly enjoyed on the subjects of civilizations breaking are The Inheritance of Rome by Chris Wickham (which we’ve mentioned here and here) and 1177 BC by Eric H. Cline (which we’ve reviewed here), who capture the overwhelming complexity of events that conspire to change even the most solid appearing structures.
One book I did not enjoy on the subject was Collapse by Jared Diamond.
*down by the sea-shore
The Finch and Pea 
I tried reading guns, germs and steel and I just couldn’t. It was boringly written, have no idea if his content was good, and no clue if there was any insight. I feel asleep after reading a few pages every time. No idea if that applies to Collapse, but oof.
Guns, Germs & Steel was more interesting. At least it made the argument that the relative differences in success (using Western nationalist criteria) between cultures was due to differences in geography and ecology, as opposed to inherent strengths/weaknesses of the cultures themselves.
I’d recommend ‘Postwar’ by Tony Judt, a history of Europe since WWII, with extensive coverage of the rise and fall of the Soviet Union and the other communist regimes in Eastern Europe.