Any international system has identifiable boundaries - beyond which actions between political units might not have an effect.

Could anyone please explain this sentence? I just can't realize what identifiable boundaries it's all about...Thanks
I'd sure like more context, but I presume that it means that no system is infinite-- it has an edge or end that can be identified as such.
One might guess that the context here is international politics. Unless the 'international system' includes all nations on the planet, it will have boundaries, outside of which exist other nations that are not part of the system. So one could reason that any action taken by the nations within the international system might have little or no effect on nations outside that system. 'Identifiable boundaries' here could be geographic ones, but maybe even more abstract boundaries that include how far reaching a given nation's political influence is.
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Thank you all, I undrestood.
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