What was the effect of japan's self-imposed isolation?

There were both negative and positive effects of Japan's self-imposed isolation. 

Negative effect: They were closed off from the world. They did not trade, this meant they had limited exotic resources. 

Positive effect: They were safe. Since they were closed off from the rest of the world, they didn't have as many threats to their region (until later on). 

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In 911, a group of vikings lead by rollo besieged paris and chartres. after a victory near chartres on 26 august, charles decided to negotiate with rollo. the talks were led by hervé, the archbishop of reims. this resulted in the treaty of saint-clair-sur-epte, which granted rollo and his soldiers all the land between the river epte and the sea. it also granted him brittany, "for his livelihood". at the time, brittany was an independent land which france had not been able to conquer. in exchange, rollo promised the king his loyalty and military assistance when needed. also rollo also agreed to be baptised and to marry gisela, the king's daughter. the territory given rollo is about the same as upper normandy.

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