I expect that it's not a theory well supported by data.
I would expect that peaceful societies are conquered by warlike societies, at a lower rate than warlike societies are conquered by other warlike societies.
Logically this ought to be true since (a) the conditions for long standing peace should necessarily mean either a protection from warmongers due to natural geography or political reality and (b) warlike societies seek out conflict and each conflict carries with it the chance of societal death.
I would expect that peaceful societies are conquered by warlike societies, at a lower rate than warlike societies are conquered by other warlike societies.
Logically this ought to be true since (a) the conditions for long standing peace should necessarily mean either a protection from warmongers due to natural geography or political reality and (b) warlike societies seek out conflict and each conflict carries with it the chance of societal death.