In the 1890's, the imperialist powers have gained control of all the important trading ports in China by these unequal treaties and have marked off areas in many of these ports as concessions under their direct administration.
Qingdao was set up and occupied by German Empire, then Japan won the possession after the First World War.
Now, qingdao is one of the most important ports of China, and the main window for exchanges between China and the Northeast Asia, including Korea and Japan.