Which physical feature made trade difficult with lands north of china

Mountains, deserts , and rivers.

Explanation:

such as mountains, deserts, rivers, and seas, made travel to and from China challenging. Other Features are  Rivers, hills, plains, deserts, plateaus, and the Himalayan mountains.

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one of the major compromises in the constitutional convention was between the small states and big states. the small states wanted each state to have the same number of representatives in congress. the big states wanted representation based on population.