On one level this ritual dance, unique to Tibetan Buddhism and performed only by monastics, might seem a colourful spectacle set to a strange cacophony of instruments, drums, and the human voice. In fact, within the Tibetan Buddhist world, Cham is far from entertainment. Rather it is a profound form of meditation which opens up the possibility of experiencing the sacred. For the audience, It falls into a category of spiritual experience known as thongdrol in which the veils which obscure the clear light of the natural state of mind momentarily fall away to give a glimpse of the true nature of phenomena. For the dancers, it is a prolonged meditation in which they visualise themselves as the deity or Dharma protector.
Both the performers and the audience are intended to approach the dance in a meditative state. (Continue reading here:)
Source: http://kagyumonlam.org/index.php/en/