What was the Frontier Thesis and why is the frontier closing significant? Explain your answer.

the conditions that made the byzantine empire vulnerable to attacks by the muslin turks were the sack of constantinople by western crusaders, the conquests of the sultanate of rum, presence of rival kingdoms and finally the set up of fiefdoms at the empire which were owned by the ghazis (turkish warriors).

yes.

explanation:

because it let the japanese know who had the upper hand in the war.

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