According to the ancient historical record known as the Nihon Shoki, the festival originated during the reign of Emperor Kinmei (reigned CE 539 - 571). The ancient records known as the Honcho getsurei and Nenchugyoji hissho reveal that a succession of disastrous rains with high winds ruined the grain crops, and epidemics had spread through the country. Because diviners placed the cause on divine punishment by the Kamo deities, the Emperor sent his messenger with a retinue to the shrine to conduct various acts to appease the deities, in prayer for a bountiful harvest. These included riding a galloping horse.
This became an annual ritual, and the galloping horse performance developed into an equestrian archery performance. According to the historical record known as the Zoku Nihongi, so many people had come to view this equestrian performance on the festival day in the 2nd year of the reign of Emperor Mommu (r. 697-707) that the event was banned.
In the ninth century, Emperor Kanmu established the seat of the imperial throne in Kyoto. This represented the beginning of the Heian Period in Japanese history. Emperor Kanmu recognized the deities of the Kamo shrines as protectors of the Heian capital, and established the Aoi Matsuri as an annual imperial event.
This festival came to be called Aoi Matsuri because aoi (hollyhock) leaves are used as ornaments not only on the people's costumes, but even on cows and horses.
This festival reproduces the procession of officials delivering the Emperor's message and offerings to the two shrines of Shimogamo and Kamigamo. In this light, the most important position held in the parade is the messenger on horseback wearing a gold sword at his side, who is followed by a train of attendants. The highlight of the procession is the parade of women accompanying the proxy of the imperial princess serving the deities. The role of this heroine is selected from among all unmarried women living in Kyoto. She must dress in the formal style of the imperial court, in other words, 12 layers of kimono, weighing 30 kg in total.
In Japanese classical literature, the word matsuri used to refer to this Aoi Matsuri. Watching this procession which faithfully observes ancient traditions, you will almost feel as if you have slipped back into the 10th Century. At 10:30, the procession leaves Kyoto Imperial Palace, where the Emperor used to work and reside until 1869, stops by at Shimogamo-jinja Shrine and finally arrives at Kamigamo-jinja Shrine around 15:30. Upon arrival of the procession, dance performances and horse events take place.