Beginning of Autumn Festival
It is a traditional festival of the Miaos. It is also known as Yanu Festival. On the very day, the Miaos in the neighborhood will gather around the fountain pool to hold various entertainments, which is in memory of the hero “Yanu” in the ancient time. The participants of the annual festival reach more than 200,000. A man and a woman dressed in traditional Miao costumes, upholding the corns and paddy, hold the ceremony for the celebration of the bumper harvest under the swing frames; then the dressed-up Miao people begin to play swing, climbing “sword ladder” and perform Lusheng dance. The young men and girls will take chance to seek their lovers. The singers sing songs with partners to greet each other. The scene is full of harmony and passion.
Source: Miao, China Cultural.org
Read more about this courtship/fertility-prosperity/show-of-bravery ritual in “Climbing a Ladder of Knives”
Further reading:
About the related symbolism of the world cosmic pillar in The Great Oak and Brother-Sister, Folklore Vol. 16
JAPANESE MYTHOLOGY & FOLKLORE 
[…] or vine-ladder-to-heaven is that of the Cosmic Pillar and the Dancing Cosmic Couple around it, see Miao Cosmic Couple and Pillar article for more on […]