When Ping Heng first visited the Ami tribal people in coastal Taiwan in 1986, she found they could reel off - and even reel - 27 different dances. Seven years later, they could barely manage a dozen. 'I don't know how many there'd be today. Fewer, certainly,' said Ms Ping, who is presenting the Formosa Aboriginal Singing and Dance Troupe at City Hall this weekend. 'A lot of tribal people, especially the young ones, are losing touch with what's happening in their own culture.' The troupe represents one of the main hopes that tribal groups have of maintaining performance traditions that have lasted several millennia of wars, weddings, and missionary interventions, but which seem to have fallen victim to the late 20th century. The group - the island's only professional aboriginal troupe - started seven years ago when dancers from the nine major aboriginal tribes got together for a one-off show. The performances generated plenty of interest from Taiwan's dance community, and from the tribal people themselves. 'It was successful, perhaps a little to their surprise, and they decided to continue,' said Ms Ping. The programme - which will also be introduced in a slide-talk this evening, where the audience will be invited to try the dance for themselves - is made up of ritual dances that have been re-choreographed for stage. The original songs can last for hours with a great deal of repetition, but here they are cut down to just a few minutes each. Making ritual performance appropriate for public performance was a new experience for everyone, she said. 'We wanted to make sure it was appropriate, and not just show business, so we worked closely with the tribal elders. But you have to make it varied.' They are careful to avoid that show-biz tag: they do not want this to be poaching or pickling of culture, but a way of repackaging the dance to make it work. 'First we get permission from the elders, and go and learn the forms from them. After rehearsing, we check back with the old people to make sure we haven't gone wrong anywhere, to make sure this is real.' The dancers are aged 16 to 46, all born in tribal villages. Many of the men have undergone the initiation ceremonies that they will be re-enacting on stage. 'Almost all of them have been through the rituals, except the boys from the Saisiyat tribe - which has already lost the tradition.' The aboriginal population of Taiwan is about 340,000 people. The myths vary, but most elders say their people arrived from Polynesia somewhere between 3,000 and 6,000 years ago. Of the nine tribes, the biggest - at about 140,000 - is the Ami, who live along the east coast. They have kept their traditions relatively well: it is the smaller groups, closer to Taipei, who have tended to forget most quickly. For a long time - whether under the Dutch, the Japanese, the Kuomintang - the city people of Taiwan had little contact with the tribal people. 'Then in 1987 when martial law was lifted, people in the cities started to change their views. We realised then that we wouldn't go back to China, and so we started to look around us more carefully, and see what Taiwan had to offer in terms of a tradition.' Ms Ping's contact with the dancers started after she joined the National Institute in Taipei in 1985, three years after it opened. 'They told us that part of the syllabus had to be Chinese folk dance. Our first thought was what on Earth we are going to do. 'Most of us had been born in Taiwan. We knew nothing about the minority cultures in China. So we thought: 'Why look at dance on the mainland, why not look at our own village cultures here?' ' Village elders were invited to the school to help them out. 'The students really enjoyed it, partly because it gave them the chance to hold hands,' Ms Ping said. 'They could also feel a real sense of togetherness, a sort of power, that they didn't easily feel with contemporary dance forms.' In 1986 Ms Ping was invited to take part in a project organised by the Anthropology Institute to notate the dances before they were forgotten. 'One of the difficulties is that the tribal festivals are at various times of the year. It is hard for the youngsters to take time off from their work in the city to go back to their village.' Often, she said, the elders compromise by squashing the festivals into much shorter time periods. So instead of spending two weeks celebrating a coming of age ceremony, it is now more often done in two days, sometimes much less. 'The one time most people get to hear the songs is during the annual ceremonies. And if they only last a few days it's hard to remember them.' This collective forgetting means the old people have much more input in the dance - and its accompanying songs - than they would have had 50 years ago, when it was seen as young people's activity. In the villages, for example, it is only the young dancers who wear the full costumes. 'Older people feel they should leave the glory to the young, so they wear less colour.' And when they are very old, she said, participants don't wear costumes at all, just normal clothes. The costumes used by the troupe are authentic designs based on photographs and memories of what was worn in the 1940s. 'Nowadays they tend to add too many extras,' said Ms Ping, handing me some photographs of people in an Ami village, wearing Nikes under their embroidery. 'It just doesn't look as good.' Interestingly, the troupe has been effective in promoting something of trend in the villages. 'I remember going to one tribal village a couple of years ago, and the elders were very impressed by the costumes we had. The next year when we went back, their costumes copied ours. They had gone back to what they used to be.' For Ms Ping, as a former dancer, and founder of her own company - Forum Dance in Taipei - being involved in ancient dance has, to her surprise, helped her understand contemporary work. 'It's easy for someone who has trained in dance to pick up techniques, whether they are contemporary, ballet, jazz or Chinese folk,' she explained. 'But what is very easy to forget is why you are dancing at all, what the original urge was. Watching this aboriginal dance has helped me remember. 'It's natural: the dancers don't act it or ask questions about its performance aesthetic or anything pretentious at all, they just do it.' Tonight's talk about the troupe will begin at 7.30pm at the Cultural Centre Grand Theatre Backstage, CR2 on floor 8. Free admission vouchers - available from enquiry desks at Cultural Centre and City Hall - are required. The Passing Of The Year: Formosa Singing and Dance Troupe. August 2-3, 8pm. City Hall Concert Hall. $100-$160 Urbtix