Why was there a kan at the entrance of the old mansion in the past

That should be called the threshold.

Threshold in ancient China is a very common architectural appendage, from several aspects of the role of the threshold it:

1, feng shui: in the traditional Chinese architecture of the entrance to the door will be equipped with a threshold, which plays a role in feng shui is to block the external unfavorable factors into the home, and to prevent the leakage of talent.

2, the role of reality: the role of the threshold is the boundary between inside and outside, at the same time, it can protect the bottom of the door, as well as block the wind blowing in from under the door. It can also prevent some small animals from entering the door when the door is open.

3, etiquette: China is a country of etiquette, where etiquette not only refers to human behavior, but also includes architectural style and rank. Threshold reflects the owner's dignity and status; in folklore, the threshold is the owner's neck or back, is taboo to step on. The higher the threshold, the higher the status. I in wuyuan, jiangxi province of an ancient building complex, see a book family threshold, than next to a rich merchant family threshold is about twice as high. It is the ancient so-called all kinds of inferior, only the book high ah.