Because of the holy thaan vocation and of influences of several religions, thaan performers have to follow a strict set of rules. In the house where a family member practices thaan, there is always an altar devoted to the thaan's ancestor in the most solemn place right in the middle room. It is placed on the center of the wall even higher than the family's ancestors. The altar is decorated and covered with brocade or laudatory writings, as well as images and prints representing the Buddha. Before starting a performance, the shamans light incense on the altar. This begins the ceremony in order to call their thaan's ancestors and helping spirits. The intention is to get every benevolent spirit  involved in the ceremony. On the altar of the thaan's ancestor, the decoration is intricate, with colorful paper images  representing swallows, which symbolic market place in heaven.

Under the rules of the religion ,the thaan performers have to abstain from touching unclean things such as animal dung, and eating beef and water buffalo meat, which for them are fetid. If members living in the same house as performers happen to consume some beef or buffalo meat, they will be sent out of the house until the following day. Otherwise they bring an unclean smell into the house and might punish them. The punishments can range from uncontrolled dancing to insanity, and the singers who have committed or insane.

The following is a story about the spirit's punishment of one such performer i heard from an informant. Ma Van An in Doc Lap commune, Quang Hoa distrct, Cao Bang province told me that in his village a female thaan singer named Nong Thi Njung went to town to live with  her husband. She stopped performing  thaan and began to eat beef and buffalo meat, so she was punished by her helping spirit and became mentally ill. Then, when she came back to her village to continue as a thaan performer, she recovered from her mental state and began to  be normal. After a certain time she left the village for the town and ate  the forbidden food again. She was punished harshly for breaking the taboo: one day she wandered around madly and jumped into a river and died. The person who told this story  emphasized that Nong Thi Njung's destiny was obilgatory; she had to be free of the spirit's will. Therefore, she received a fatal punishment.

The thaan practitioners have other taboos which, if transgressed against, involve a serious violation. The guilty parties are punished by the thaan ancestors. As a result, they are forbidden to enter the thaan vocation. Ly Thi Hoa in Doc Lap commune could no longer practice thaan at the age of 71. She used to be a well-known performer in the region and had many invitations from her villagers. To get  a higher position in the thaan vocation, she organized the third ceremony of lau put. During the rite,however she violated a rule. On atable, twelve bowls of different kinds of food and other things were placed. The bowls were covered by cloth. According to the rules, she had to pick up a bowl at random and eat whatever was in it. She refused to eat the chosen food because it was awful. Afterward her thaan singing ability was lost, as well as her power and popular reputation, and her respect. She could not practice thaan anymore. When I went to see her in the middle of the seventh month festival in1997, she sang and practiced a performance on that day in front of the thaan ancestor's altar at her house, from the first cock crow until midnight of the following day. She looked sad and weak, like a very sick person. When I asked her about her vocation as a thaan practitioner, she did not want to talk. Maybe she didn't want to remember her violation. Unlike other thaan singers, who can sing in the state of ecstasy without a ritual ceremony, put Hoa does not sing any songs. She confesses that she does not remember any words on her own; only in ritual ceremonies , after she calls helping to return and guide her, can she sing the songs. Put Dien in Ha Quang or put Binh in the town of Cao Bang can sing without the real ritual ceremonies.
What they need for singing without a ceremony is to light some incense in order to get permission from their thaan ancestors.

During a long performance, the thaan practitioners communicate with participants in a state of ecstasy. They speak, but do not fully understand and remember after returning to consciousness. While performing, no one is allowed to touch the practitioners, especially when they shake the rattle, for symbolically, at that moment, they are riding a horse  on the journey to the other world .Anyone who violates the taboo fills down from the horse and is hurt or gets sick.

The performers differ in the spiritual nature of their vocation. Depending on the sacredness and secularity of the thaan vocation, we can classify the thaan performers into two groups:(1)successors,(2)put dip.
1. successors are appointed by deceased masters who are also called the 'hereditary transmitters of their family and community vocation. This tradition is passed down from generation to generation .When the than singers pass away, they transmit their vocation to someone in their family or to a community member. The selected persons are supposedly ninh mau (people with light souls [vn]). That is , spirits can easily enter their souls and possess them. Once they are chosen as hereditary thaan practitioners, they cannot refuse it in any way. If they make an effort to resist, they and their family members will have frequent misfortune. They will either get sick or when they raise farm animals such as poultry or livestock, these animals will perish as well. If they try to plant crops the result will be that all the plants will turn yellow, wither, and then die.

During my fieldwork, I went to see a few thaan performers in Ha Quang, Hoa An,and Quang Hoa districts, and the capital town of Cao Bang province.The shamans and their relatives told me nearly the same story about the power of their thaan ancestor apirits.
Their deceased ancestors (great grandmother, grandmother, or mother) were thaan performers. After death, they become spirits of thaan who, one day, return to the persons who are subject to the spirits' attacks. The chosen individuals start to nhay xuong (come down[vn]). This expression describes the dancing movement and action of the selected persons by the spirits. They begin to dance madly. This means that their than ancestors have returned from invisible worlds to enter them, causing them to go up to a beam of their house or a tree, or to do thing that they cannot do in a normal state, such as climb up a cliff. After these apparently neurotic activities, they prepare a tray of offerings to put on altars, burn incense, and pray to spirits. Then, they sing and dance as if they perform a ritual ceremony, from that moment on they are seen as thaan practitioners. The helping spirit and the thaan ancestors return to teach them how to practice the  thaan ceremonies in their dreams and appear in them when ever  pray to them. The spirits follow them wherever they go to perform in order to assist and guide them.

To be a professional thaan performer, they must undergo training both with their invisible thaan ancestors and with human thaan teachers. To transmit the vocation , the spirits teach them in their dreams. Eventually, the new practitioners learn by heart the spirit's songs and master the techniques of the performance from dreams. They still have to perfect the techniques more and more with thaan masters in real ritual ceremonies, so they go to their masters' hsmes to learn, accompany them to thaan performances, and sing with them.

The real thaan practitioners , in the opinion of most people, know many things in  estate of ecstasy. They can predict, intercede  with supernatural powers, sing for several hours a number of songs, and play musical instruments. They also know temporarily how to compose rhymed verses and are capable of clever repartee with an audience in a given situation of the ritual ceremonies. After their novicehood and apprenticeship, the new practitioners are able to master the thaan ceremony: to experience trances, sing songs and perform ritual processes. They choose an auspicious date to organize the first ceremony of lau put (being accepted by their mundane masters, as well as by the god of heaven and the thaan ancestors, and later on, requesting promotion). In the lau put rite, the biggest among the thaan ceremonies, the practitioners invite all villagers, their relatives, and their colleagues (other thaan singers around the area), and a taao-a very powerful religious master of the highest level to conduct the rite. The religious specialists in the ceremony sing for three successive days in the new thaan performer's honor and to serve as witnesses in the recognition of the  new practitioners. The spirits and the community  now accept them as ''official'' thaan singers. After three days of singing by many performers, they are given a robe, hat, and waistband by their masters. Then they go to a field to pray to the spirits of the four directions, asking for permission to be the thaan performers. Returning home, they are tested by jumping into a fire and sitting on sharpened bamboo spikes. If they are  not injured or hurt, that means the spirits have allowed them to be a sacred and powerful performers who are able to intercede with the invisible spirits, and can experience unusual and even somewhat supernatural phenomena. Their masters, families, and villagers acknowledge that they have become performers who have been chosen by thaan ancestors. They kowtow to the new practitioners and show them respect. From that moment on, the thaan singers have the authority and license to practice thaan themselves. They are moved to tears because they have begun their new lives as shamans and religious folk singers. This event is also the pride of their families among community members, for the singers inherit their ancestors' vocation and fulfill the calling of the spirits. They also take an oath that they will not commit sins such as fighting with their parents and relatives, stealing, and being boastful. Neither wild they murder or even kill animals.

Hatbands mark the hierarchy of the thaan practitioners. After the initiation ceremony, the thaan performers wear hats with five strpes. Later on ,after each lau put rite, they add two more hatbands,that is from five, to seven, to nine and eventually to fifteen, the highest number possible, only the thaan performers who are wealthy and are supported by their families, relatives, and friends can afford all these lau put ceremonies. In some districts of Cao Bang, the hatbands of the thaan practitioners are not the same. At the first initiation ceremony, practitioners are given hats with one hatband, and every other lauput ceremony, they add one more hatband to their hats. Thus, by looking at their hats we can recognize the number of their lau put rites,  know their thaan performing experiences, and their status among the destined shamans.
2. put dip are people who love to sing thaan. They are the thaan performers of their own free will and are self-made.They sing the thaan songs merely for pleasure and entertainment, and they usually accompany thaan masters to their performances to sing with them. They try to learn the traditional techniques of the thaan performances but can not enter trance. They are not given the power to intercede with spirits, and thaan's ancestors do not grant them the status of thaan practitioners. They cannot master the thaan ceremonies themselves and neither are they invited to perform the ritual by their community members.

Many people try to learn how to sing and  perform thaan but not every learner becomes the thaan performer. Some performers are well known for a certain time but then lose their popularity. They then perform a ceremony in order to return to their masters and ask to train with them again. Whenever the new performers become masters, they are surrounded with con so or con huong or con hoa (young students). Con huong are sent by their parents to study under the thaan masters' patronage. These young students follow their masters to the ceremonies, help them to prepare the offerings,and learn how to sin and perform a thaan ceremony. Some of them sing for pleasure, but they stop accompanying their thaan masters when they get married. The other ones are called by the thaan ancestors to the vocation and can experience trance during the performance. They separate from their masters when they are able to master the traditional performing techniques .Thaan masters have many adopted children whose disease they heal or whom they save from bad luck. On special occasions ,on the lau put  rites and on New Year's day, these children bring gifts to their masters as a sign of their gratitude. For instance, put Dien, a female practitioner in the district of Ha Quang province of Cao Bang performed the ceremony for her 48th adopted child, which I observed in summer of 1997 .There are many pople who practice the thaan ritual. According to statistics kept by the Culture and Information Department of the autonomous region of Viet Bac before 1976, the a large number of thaan performers in a village is five (Nong Van Hoan 1978 :13). The fact is that villagers choose one among a large number of singers to practice thaan for them. The life and prosperity of households are thought to depend on the reputation and power of performers. Their voice and their behavior as individuals are judged by the masses during performances and afterwards .During a performance, if they lose their voice, forget the songs, cannot make the tradition fit the real ceremony , or cannot answer the audience's questions, they will be judged inadequate and could lose their reputation. As shamans, the thaan practitioners sometimes entertain people (La Van Lo,Ha Van Thu 1984:30).Through them, their villagers want to have contact  with invisible spirits. They hold a khaai bjook (selling of flowers)to tian (female charming spirits) so that the lay people have a chance to meet the spirits, sing, and dance with them. They also have the linaan (playing with swallows) performance in which swallows take the lay people's souls to visit paradise in the moon or heaven. The other kind of the entertainment performances is dee lau (offeing of wine),w here the deceased souls make offerings to the gd of heaven after a trip of hardship through deep rives, high mountains, places full of evils, and demons in order to reach  heaven. Also,girls who are not successful in love and marriage can make friends with heavenly people, or even get married in heaven, and men can take time to spend with tian for a while with the help of the thaan practitioners.
Thaan performing is a vocation given by spirits but it is also a job for practitioners to earn a living by. People do not like the singers who ask for too much money and offerings as payment for their performances. They are more respected if they do not demand a fee and are satisfied with any payment. However, households usually pay them according to the common rate. Put Dien whom I met during my stay in Ha Quang was busy with invitations because of her easy-going character, and was very happy with what the households gave her just as a symbol of their gratitude to her singing and practicing. By contrast, put Nau, who lives near  put Dien ,was rarely invited to perform because she demanded high payments. Generally, households pay a part of the offerings, including one chicken, one duck, a section of pork head, seven bowls of rice, and from100,000 to120,000Vietnamese dong (around 8-10US S ) in1997, and treat the performers to several lavish meals during their performances.