Who were the main enemies of the Mongols?

Siege warfare, for example, became necessary when the Mongols came up against such enemies as Song China, Persia, and Eastern European kingdoms.

Explanation:

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the virginia plan called for three branches of government and two houses of congress. representation in each house would be determined by population. the new jersey plan called for three branches of government and a single house of congress. each state would have an equal vote.