Unlike old houses, most quadrangles are not allowed to circulate for historical reasons. A set of quadrangles, the family living in it may only have the right to use, and the actual property right belongs to the Housing Authority and belongs to public houses.
Only twenty or thirty sets of quadrangles can circulate in Beijing every year. Courtyard houses with property rights often have complicated property rights. Often a few people, even a dozen people, have a quadrangle. If one person opposes the price or is unwilling to sell, the sale cannot be completed.
Siheyuan, also known as Siheyuan, is a traditional high-level quadrangle-style building in China. Its pattern is that a courtyard is surrounded by houses, usually consisting of a main room, an east-west wing room and an inverted-seat room, and the courtyard is surrounded in the middle from all sides.