Dancing Triangles is mounted onto a soft canvas backing so it can be hung on the wall without stretching. This backing also allows the rug to be used on the floor.
Once the backing is sized and dyed, it has to be pinned to the rug with very large safety pins. 
Once the entire backing is pinned to the rug, I start sewing the backing to the rug with fiber that might have been used in the rug, so it won't show on the front. 
I try to stitch so that there is no more than about 4" of run unattached at any point in the backing. 
Here the backing is mostly attached. It needs another row of stitching at the top and bottom, in the middle of the rod pocket. It could be mounted horizontally, too.