Nowadays, Chinese people would like to say "做东" (zuò dōng) when they treat guests in a restaurant. So why is "treating guests" called "做东" in Chinese?
In ancient China, people build south-facing houses. In some rich or important people's houses, they will build a reception room in the middle of the whole house. They put two seats in the reception room, one facing east and the other facing west. When the host receives a guest, he often lets the guest sit on the west and the host himself sits on the east. Therefore, "坐东" (zuò dōng) refers to the host. As the word "坐东" is relatively less elegant in written Chinese, it's changed into "做东" later, a homonym of the former one.
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