generally do not "collapse"
(the Spanish Empire is a notable exception)
but slowly decay
and/or dismantle themselves
like the French and British empires
which limp on today.
The "Collapse of the Roman Empire"
is piffle. It began to degenerate
even before it reached
it widest limits and strongest sway -
while Rome was still, in theory, a republic.
The Ottoman empire took at least
two centuries to wither away.
Ebb and flow and ebb are more the norm
than complete destruction by a storm.