Here is a link of an article I found stating that Soma was Cannabis. However upon reading it there seems to be evidence that Soma has changed in time... This makes me believe that different psychoactive plants were used in different times and places.
Still fascinating to see how important it has been throughout religions in the past. Makes me sad to see what has remained in the religions of our present day society.
"It permits you to see, more clearly than our perishing mortal eye can see, vistas beyond the horizons of this life, to travel backwards and forwards in time, to enter other planes of existence, even (as the Indians say) to know God." R. Gordon Wasson