What does "Nine is the ultimate number" mean?

It means that nine is the greatest.

In traditional Chinese culture, "nine" is an extremely important number.

It is both a "yang number" and a "pole number". It refers to the height of the sky as "nine layers" and refers to the extremes of the earth as "nine springs". Nine is the most worshiped mysterious number in faith.

At the same time, nine has the same pronunciation as "jiu", which means long-lasting health.

In ancient times, if a major crime was committed, such as treason or rebellion, the nine tribes would be implicated. This crime first came from the Shang Dynasty. If one person was guilty, his parents and wife would be punished. When King Wu of Zhou launched an army to attack the Shang Dynasty, one of the crimes was to punish the clan members.

It can also be seen from here that the ancients hated this criminal law, but rulers of all dynasties still used this criminal law to strengthen the rule of imperial power.

During the Qin Dynasty, the three tribes of Yi were most commonly used. The three tribes here refer to the father's family, uncles and uncles, and descendants. However, half of the men were executed, and the women in the family would join the Jiaofangsi as prostitutes. In the Han Dynasty,

During this period, the country was in turmoil and the criminal law was severe. In order to strengthen the control of rights, the three Yi tribes gradually became the nine implicated tribes. If one person makes a mistake, the entire family will be implicated.