Read the text and tell in your own words how Tibetan opera was formed and what its characteristics are.

Tibetan opera is a very huge drama system. Due to the differences in natural conditions, living customs, cultural traditions and dialects in different regions of the Qinghai-Tibet Plateau, there are many artistic varieties and schools. Tibetan opera is the mother of Tibetan opera art, which was spread to Qinghai, Gansu, Sichuan, Yunnan and other Tibetan-speaking areas through monks and pilgrims who came to the Uygur Tibetan temple for further study, and formed three branches: Huangnan Tibetan opera in Qinghai, Gannan Tibetan opera in Gansu and Seda Tibetan opera in Sichuan. Tibetan operas are also circulating in Tibetan inhabited areas in India, Bhutan and other countries. The Tibetan name of Tibetan opera is Ajram, which means "fairy". It is said that Tibetan opera was first performed by Seven Sisters, and most of the plays were fairy tales in Buddhist scriptures, hence the name. Tibetan opera originated from Tibetan religious art in the 8th century. /kloc-in the 0/7th century, it was separated from the religious ceremonies in monasteries, and gradually formed a life-like performance with singing as the main part, combining basic programs such as singing, reading, dancing, table tennis and acrobatics. Tibetan opera sings loudly and forcefully, basically because people set the tone, and every aria is helped by people. Tibetan opera was originally a square opera, accompanied by a drum and a cymbal, and there were no other musical instruments. Tibetan opera usually lasts for three to five days, and there is no casual stage. It is fun to be surrounded by a group of people. The performance of Tibetan opera is generally divided into three parts. The first part is the "pier", which is mainly the opening performance of singing and dancing to worship the gods; The second part is Bear, which mainly shows the legend of the play. The third part is called "Tashi", which means blessing and welcoming good luck. According to legend, there are 13 Tibetan operas that are often performed, such as Princess Wencheng, King Nuosang, Langsa Wenbang, Zhuowasam, Sujinima, Baima Wenba, Dunyue Dunzhu, Naomi Gengdeng, and Riqiong Wa and Yun. Tibetan opera has only one costume from beginning to end, and the actors don't wear makeup, mainly wearing masks.