In ancient times people believed that all natural phenomena could be explained by this theory. Numbers were also related to this theory. Even numbers belonged to Yin and odd numbers to Yang. The ninth day of the ninth lunar month is a day when the two Yang numbers meet. Therefore it is called Chong Yang. Chong means double in Chinese. Chong Yang has been an important festival since ancient times.

The ninth month also heralds the approach of winter. It is a time when the living need warm clothing. Additionally, the Chinese sons and daughters extended this to make the festival a time for providing winter clothes for their ancestors. Therefore, the Double Ninth Festival, also a festival that reminds us to respect the olds.

Also, as double ninth was pronounced the same as the word to signify "forever", both are "Jiu Jiu", the Chinese ancestors considered it an auspicious day worth celebration. That's why ancient Chinese began to celebrate this festival long time ago.

As recorded in a historical book of the sixth century, in ancient times, there was a man named Huan Jing. He was learning the magic arts from Fei Changfang, who had become an immortal after many years of practicing Taoism. One day, the two were climbing a mountain. Fei Changfang suddenly stopped and looked very upset. He told Huan Jing, on the ninth day of the ninth lunar month, disaster will come to Huan Jing’s hometown. Thus, he must go home immediately and remember to make a red bag for each one of his family members and put a spray of dogwood on everyone. Then he must all tie his bags to arms, leave home quickly and climb to the top of a mountain. Most importantly, he must all drink some chrysanthemum wine. Only by doing these then his can family members avoid this disaster.
On hearing this, Huan Jing rushed home and asked his family to do exactly as his teacher said. Then, the whole family climbed a nearby mountain and did not return until the evening. When they got back home, they found all their animals dead, including chickens, sheep, dogs and even the ox.

On Double Ninth Festival, people would like to drink chrysanthemum wine and have chrysanthemum cakes.  The chrysanthemum is a plant often used as a Chinese herbal medicine. People in ancient times believed that chrysanthemum could drive away evil spirits and prevent one from getting a chill in late autumn. Besides, the Chinese word for wine is Jiu, a homonym of the Chinese word for long, symbolizing longevity. Another special food for this festival is chrysanthemum cakes. The Chinese word for cake is Gao, a homonym of the Chinese word for high, symbolizing progress and promotion at work and in daily life and improvement in life year by year.

In 1989, the Chinese government decided the Double Ninth Festival as Seniors' Day. At the waterside or on the mountains, the seniors will find themselves merged into nature. In the tradition of respect for elders in China, the government calls on relevant department throughout the country to organize activities to help senior citizens. This includes offering financial aid to those with difficulties and care for those who have on children.

During, the Double Ninth Festival Garden Gathering, people would gather in the Park of Eight Great Temples (Badachu) since 1988. Each year, it attracts more than 200,000 active elder participants with its entertainment and other activities, including free health care consultation offered to the elderly by Beijing’s major hospital.

Climbing mountains
On the Double Ninth Festival, people customarily Climb Mountains, appreciate chrysanthemum flowers, drink chrysanthemum wine, and eat double-ninth cakes. As it is also known to be an "Old Men Festival", going out is meant to improve old people’s health on the day of the festival.

Family get-togethers
The Double Ninth Festival is also a time for family get-togethers. It is an occasion to remember one's ancestors, the sacrifices they made and the hardships they underwent. Often, family outings are organized during which people search to renew their appreciation of nature and to reaffirm their love and concern for family members and close friends.

Going out
The festival is held in the golden season of autumn, at harvest-time. The bright clear weather and the joy of bringing in the harvest creates an happy atmosphere. It is usually perfect for outdoor activities. Therefore, considered as the last outing of the year before the onset of winter, the Double Ninth Festival is for people to go climbing to get some exercise as well as enjoy the autumn scenery.