Yunnan Jingpo's Munaosong Festival who knows how it came about and when it is held?

"Menaw Zong" is the name of a large-scale song and dance. Participants in the dance as many as thousands to tens of thousands of people, usually to dance four days and four nights. In this kind of dance, the leader of the dancers, who has a long peacock feather on his head, leads the dancers to dance around the three wooden boards that are erected in the middle of the dance floor. The leader cannot be changed at random, nor can he leave the stage in the middle of the dance. The band follows the leader, followed by a long line of dancers. Accompanied by elephant foot drums, gongs, bamboo tubes and other musical instruments, the men dance with long knives and the women wave red cloths, dancing and singing rhythmically and neatly. The long dance team sometimes like a dragon roll, sometimes like flowers in full bloom, quite spectacular. Meg brain song is a traditional festival of Jingpo people in Dehong, which means "dancing in a big group". It is usually held on the 15th day of the first month of the lunar calendar and lasts for four to five days. At that time, people dressed in festive costumes, from all directions to participate. Jumping eye brain long song to be held in a wide square or lawn. People first in the center of the field erected colorful eye brain column, column height of about 20 meters, made of chestnut wood, painted with exquisite patterns. On the left side is a square divided into four triangles, and on the right side is a fern, because the fern buds are like clenched fists, and the leaves are like rows of arrows, which is regarded as a symbol of unity and advancement by the people of Jingpo. Between the western pillars, two silver knives are placed crosswise, symbolizing the character traits of the Jingpo people, who are brave and resolute, and who are capable of fighting through thorns and thistles. On both sides of the pillar, there are two 8-meter-high wooden boards, which are painted to symbolize the prosperity and good fortune of the descendants. The upper horizontal plaque depicts the Himalayas, which are said to be the birthplace of the Jingpo people, while the lower horizontal plaque depicts crops and livestock, symbolizing the desire and pursuit of a better life in the future. There are two high platforms in front of the Megamind pillars, from which it is said that one can look out over the Himalayas, the home of the ancestors, and look to the future. Around the platforms are wooden stakes on which eight gongs, drums and other musical instruments are hung to indicate auspiciousness. The outside is surrounded by two bamboo fences to indicate victory. The ceremony begins with the firing of cannons, the sounding of sheng pipes, drums and music, and the exchange of gifts of eggs and rice wine by compatriots of the Jingpo and other ethnic groups, and the offering of purple glutinous rice poi wrapped in banana leaves to the guests. In the midst of the joyful sound, the dance is led by two highly respected old men wearing dragon robes, "woodpecker hats" and long knives, who change their dance postures and formations to the beat of the music and drums. Behind them, there are thousands of people dancing one after another. The women dance with flower handkerchiefs, fans or garlands, twisting their waists and swinging their dresses decorated with chains of silver bubbles. The men wore white headgear decorated with red tassel celluloid, dressed in white shirts and black pants, holding a long, shiny sword, looking heroic. They dance with firm and robust steps, shaking the mountains and rivers. Han compatriots came, Dai compatriots came, Achang, De'ang, Lisu compatriots also came, we are happy, joyful picking, from time to time issued "Oh la!"　"Oh la!" cheers. The queue is sometimes like a long dragon, sometimes like a fern flower bending, symbolizing strength and unity. On the dance floor, "Bazaar" is blown vigorously, gongs and drums sound together, and the sound of majestic and magnificent dance steps shakes the mountains. The long history of the Megamind Song is said to have been taught by the God of the Sun. The Jingpo people had a hero named Ning Guanwa, who was told by his parents before they died: "After we die, you have to dance and hold a ceremony to send off your soul, so that we can turn into the earth, and you can become a human being to reproduce and survive on it". Ning Guan Wa was about to go to the Sun Country to learn the dance, but he saw the birds holding a meeting of eyes and minds under a yellow fruit tree, and it turned out that they had already learned the dance at the invitation of the Sun God. He quickly learned the dance from the birds, drew the dance routine on the chestnut wood columns, and at the foot of the Himalayas to set aside the dance field, held the first Megamind song, and from then on to the earth.