In Chinese tradition, certain numbers are believed by some to be auspicious or inauspicious based on the Chinese word that the number name sounds similar to. Nine is considered a good number in Chinese culture because it sounds the same as the word "long-lasting.
The number 9 was historically associated with the Emperor of China, and the number was frequently used in matters relating to the Emperor, before the establishment of the imperial examinations officials were organized in the nine-rank system, the nine bestowments were rewards the Emperor made for officials of extraordinary capacity and loyalty, while the nine familial exterminations was one of the harshest punishments the Emperor sentenced; the Emperor's robes often had nine dragons, and Chinese mythology held that the dragon has nine children. It also symbolizes harmony.
The dragon often symbolizes the Emperor, and the number nine can be found in many ornaments in the Forbidden City. Nine is strongly associated with the Chinese dragon, a symbol of magic and power.