"Father Pat Ahern had a vision for the company more than 20 years ago and believed our style of dancing should be open to other influences," says artistic director Oliver Hurley. "In the early years he invited choreographers like the Argentinean Roberto Domico to workshop with the company and in 1986, after the professional company was formed, he invited Jonathon Burnett to create An Mhaigdean Mhara."

This was Siamsa's first success, and brought them to the Dublin Theatre Festival for the first time. Burnett, a dancer with Irish National Ballet in Cork, was the first in a list of collaborators that has included the ballet of Anne Courtney, flamenco of Maria Pages and the contemporary release technique of Mary Nunan.

Oileán is the company's latest work, that recreates traditions and customs from the Blaskets through the daydreams of a modern-day visitor to one of the uninhabited islands. Choreographed by Cindy Cummings, whose credo cites influences such as contact improvisation, it features many contemporary choreographic devices and techniques to enliven the depictions of community. A set-dance might seem to be winding its way through an obvious sequence until suddenly the group lurches to the side mid-pattern, dragging a bare foot while sweeping the ground with trailing arms.

"Some partnerships worked better than others," says Hurley. "When making some of the earlier pieces we didn't have the training and technique to really benefit fully from the collaboration. These days we are more equipped and vocal about what we want."

He cites Clann Lir with Mary Nunan as a particularly successful collaboration. Nunan's movement vocabulary is based on release technique, which minimises physical tension in the search for clarity and fluidity and the efficient use of energy and breath. This vocabulary matched Siamsa's fluid style of dancing.

Nunan's teaching at the University of Limerick, where she is a lecturer in contemporary dance, has also influenced ex-Riverdance stars Colin Dunne and Jean Butler. "Whereas before my style was very muscular and lifting out of the floor, now it's more released into the floor," Dunne says. "It's like thinking of the body hanging down as opposed to being held up. It's a subtle difference to look at, but a huge shift to find physically."

Both Dunne and Butler (who will present a solo performance at Project later this year) talk of a process of deconstructing their vocabulary to find the essence of its identity. Cummings uses a similar process in Oileán, by underpinning and driving the action with the pulse of heeltaps, whether by stationary standing figures or schoolchildren seated at their desks. This one ingredient of Irish dancing technique becomes a thread through Oileán that is both visual and rhythmical.

In the past the yardstick of success for choreographers mixing idioms was a fusion of the smooth upper body of ballet or contemporary dance with the articulate feet of Irish dancing. But just as our perceptions of historical identity and relationship with tradition are more refined, depictions of that connection must be equally complex. In Oileán the weaker choreographic moments leach through when simplistic solutions are sought.

When the curtain rises on Oileán, a group of black-clad dancers clatter through a humdrum life taking sharp right angles to avoid each other. The basic ingredient is normal footsteps, with flurries of staccato taps adding spice. The visitor, danced by Blathnaid Nolan, emerges from the bustle of modern life, soft-armed and moving in more fluid and organic lines. Although the contrast with the rigidity around her is striking, it also seems quite obvious, and her lightweight movement is less convincing than the tableau of more traditional steps.

While the alchemy isn't yet perfect, Siamsa is committed to continual experimentation. First there's the outreach programme - "Tithe Siamsa" or folk academies - set in areas of Kerry where there are rich pickings in folk culture. Training in traditional dance, singing, mime and movement is delivered over three years, culminating in a production that portrays the folk life of the regions in which each Teach Siamsa is located. Some pupils are offered places in an advanced class in the theatre in Tralee and may become members of the Community Company. In addition Siamsa offers a BA in Folk Theatre Studies with the Institute of Technology, Tralee, and some dancers have completed the MA in contemporary dance at the University of Limerick. "We thought we might have lost those dancers," says Oliver Hurley. "But they came back and are interested in continuing to work within the Siamsa idiom."

Some of their experience has been fed into rEvolution, a multidisciplinary project between Cummings, visual artist Andrew Duggan and a small group of Siamsa dancers. This began life as a research project in 2003 and attracted the company's first Arts Council support for performance (Siamsa receives a revenue grant for the theatre but not for the company). Success demanded a further step and, with the help of a second Arts Council grant, the material and methodologies evolved into a performance that will be part of this year's Dublin Fringe Festival.

Artistic director Wolfgang Hoffmann sees potential in the new boundaries Siamsa is setting. "I didn't know much about Siamsa's work before, and was told, in slightly snobby tones, that they are the carriers of an old Irish dance form and mainly perform it for tourists. I met some of the dancers at a public talk with [ DV8 director] Lloyd Newson and they talked to me about their project, which I thought was intriguing. After discussion with Cindy, I decided to include them in the festival on the basis that these artists truly challenge their existing practice. They will perform now at the Mansion House, a fairly symbolic location, and I have given them a special recommendation in the programme along with Cois Céim, which I hope will give them a healthy brush against the grain."

Feeding rEvolution back into the company's main work is the next task, and one idea is creating an experimental wing of the company. Hurley is also keen on revising some of the main repertory. "Jonathon Burnett contacted us last year about revising An Mhaighdean Mhara," Hurley says. "It would be interesting to rework older pieces since we have evolved and are now better trained and more fluent in our collaborations."

Siamsa has always seemed to exist on a cultural blindspot, and Hurley recognises the need to promote the company. "We have never felt part of the rat race and have been able to give time to our work. The downside is that people ask why we don't do this or that and we reply that we have been. For years."

There is a restlessness about Siamsa as it broadens the focus of folk-theatre. The move into markets such as the Fringe will increase understanding of our National Folk Theatre. Evolving its idiom enriches the past as well as the present.