Who received important ports, cities, and concessions in Southeast Asia in return for not interfering with British shipping?

China

Explanation:

The Chinese are the South East Asian country which received important ports, cities, and concessions in return for not interfering with British shipping.

During the First Opium War the Chinese didn’t interfere with the British importation of weapons and other food materials which were needed for their army which made the British repay the goodwill by setting up several structures for the Chinese people.

it was on the rise and doing very well and would continue to do well until the great depression from 1929-1939

explanation:

damn girl thats not really your friend then. : /