Dance Movement Psychotherapy (DMP) has been called a “bridge of contact and vehicle for communication” with people with autism.
In this short video by Dr. Christina Devereaux, she illustrates how “the major strength that dance/movement therapy has in working with people with autism is its ability to produce treatment outcomes in the area of social relatedness, especially in the formation of relationships” :
In the same vein, this clinical info sheet from the American Dance Therapy Association describes the mechanisms which allow DMP to be a bridge of contact with people with autism. 
More recent research also supports the use of DMP in helping in the area of the triad of difficulties in autism: communication and social skills as well as flexibility of thought and imagination.
Dance Movement Psychotherapy 