Dragon Boat Festival

The Dragon Boat Festival is a traditional Chinese holiday that occurs on the fifth day of the fifth month of the Chinese calendar, which corresponds to late May or early June in the Gregorian calendar. The holiday commemorates Qu Yuan who was the beloved prime minister of the southern Chinese state of Chu during the Warring States Period, about 600 B.C. to 200 B.C., and is celebrated by holding dragon boat races and eating sticky rice dumplings called zongzi, which were southern Chinese traditions. Dragon Boat Festival integrates praying for good luck and taking respite from the summer heat.
In September 2009, UNESCO officially approved its inclusion in the Representative List of the Intangible Cultural Heritage of Humanity, becoming the first Chinese holiday to be selected. 

History
Origin
The fifth lunar month is considered an unlucky and poisonous month, and the fifth day of the fifth month especially so. To get rid of the misfortune, people would put calamus, Artemisia, and garlic above the doors on the fifth day of the fifth month. These were believed to help ward off evil by their strong smell and their shape (for instance, calamus leaves are shaped like swords). 
Hanging wormwood leaves on top of a door, meant to deter insects
Venomous animals were said to appear starting from the fifth day of the fifth month, such as snakes, centipedes, and scorpions; people also supposedly get sick easily after this day. Therefore, during the Dragon Boat Festival, people try to avoid this bad luck. For example, people may put pictures of the five venomous creatures (snake, centipede, scorpion, lizard, toad, and sometimes spider on the wall and stick needles in them. People may also make paper cutouts of the five creatures and wrap them around the wrists of their children.

 Big ceremonies and performances developed from these practices in many areas, making the Dragon Boat Festival a day for getting rid of disease and bad luck.
17th century depiction of Qu Yuan
Qu Yuan
 
The story best known in modern China holds that the festival commemorates the death of the poet and minister Qu Yuan (c. 340–278 BC) of the ancient state of Chu during the Warring States period of the Zhou dynasty. A cadet member of the Chu royal house, Qu served in high offices. However, when the king decided to ally with the increasingly powerful state of Qin, Qu was banished for opposing the alliance and even accused of treason. During his exile, Qu Yuan wrote a great deal of poetry. Eventually, Qin captured Ying, the Chu capital. In despair, Qu Yuan committed suicide by drowning himself in the Miluo River.
It is said that the local people, who admired him, raced out in their boats to save him, or at least retrieve his body. This is said to have been the origin of dragon boat races.[15] When his body could not be found, they dropped balls of sticky rice into the river so that the fish would eat them instead of Qu Yuan's body. This is said to be the origin of zongzi. 
During the twentieth century, Qu Yuan became considered a patriotic poet and a symbol of the people. He was promoted as a folk hero and a symbol of Chinese nationalism in the People's Republic of China after the 1949 Communist victory in the Chinese Civil War. The historian and writer Guo Moruo was influential in shaping this view of Qu. 
Wu Zixu
Another origin story says that the festival commemorates Wu Zixu (died 484 BC), a statesman of the Kingdom of Wu. Xi Shi, a beautiful woman sent by King Goujian of the state of Yue, was much loved by King Fuchai of Wu. Wu Zixu, seeing the dangerous plot of Goujian, warned Fuchai, who became angry at this remark. Wu Zixu was forced to commit suicide by Fuchai, with his body thrown into the river on the fifth day of the fifth month. After his death, in places such as Suzhou, Wu Zixu is remembered during the Dragon Boat Festival.

Cao E
The front of the Cao E Temple, facing east, toward the Cao'e River in Shangyu, Zhejiang
Although Wu Zixu is commemorated in southeast Jiangsu and Qu Yuan elsewhere in China, much of Northeastern Zhejiang, including the cities of Shaoxing, Ningbo and Zhoushan, celebrates the memory of the young girl Cao E (130–144 AD) instead. Cao E's father Cao Xu (曹盱) was a shaman who presided over local ceremonies at Shangyu. In 143, while presiding over a ceremony commemorating Wu Zixu during the Dragon Boat Festival, Cao Xu accidentally fell into the Shun River. Cao E, in an act of filial piety, searched the river for 3 days trying to find him. After five days, she and her father were both found dead in the river from drowning. Eight years later, in 151, a temple was built in Shangyu dedicated to the memory of Cao E and her sacrifice. The Shun River was renamed Cao'e River in her honor. 
Dragon boat races at Dajia Riverside Park in Taipei
Cao E is depicted in the Wu Shuang Pu ("Table of Peerless Heroes") by Jin Guliang.

https://en.wikipedia.org/wiki/Dragon_Boat_Festival