This is an antique silk warp "Rainbow" Senna measuring approximately 4'9"x7'3" from the last quarter 19th century. While newer renditions of silk warp Senna rugs exist, most production seems to be isolated between 1860-1910. Within antique Persian Rugs, the silk warp Senna is by far one of the easiest to identify:
Below: Other than the common medallion field with covered repeating designs, consistently silk warp Senna rugs are often found in the 5'x8' size or smaller, feature high knot count in the vicinity of 200-400 KPSI. This particular example has approximately 320 kpsi.
Below: However, perhaps the most apparent and unique characteristic of such a rug is the multi-colored or "polychrome" silk warps which comprise the structure and fringe. Silk warp Senna rugs are often nicknamed the "Rainbow" Senna, as the fringes are often found to have anywhere from 5-8 different colors such as purple, yellow, ivory, green, red and blue.
Below: A close up detail of one corner. From lower left to upper right: note the yellow, purple and green fringe (or foundation). This piece also has overcasting to prevent end loss.
Below: While the foundation warps are silk, the pile is almost exclusively wool.
Below: A close up detail image of the edge of the rug. If original, Rainbow silk Senna rugs often have a two cord silk selvage sometimes the color of which would be in the "purple" family.
Below: Looking closely at the reverse side of the rug, we can see a bit of the foundation warp threads showing through the knots. See how a slight overcast is seen running vertically through the rug taking on a similar tone of the warp beneath.
One or more example(s) photographed above courtesy Dilmaghani & Co.
inventory of their NY oriental rug Warehouse
or NY showroom of Oriental