This rug is discussed in the sotheby spring sale thread in the Auctions Worldwide Topic Area. The border detail on the left is from another unusual rug that is also hard to attribute. But itís sure neither of these rugs deserves to be labeled 'trans-caucasianí, which a meaningless term better forgotten.
These two rugs are very different, the only similarity they share is the border design. As far as I can tell, the sotheby example is based on the other's, which probably had as its prototype the typical transylvanian star and cartouche.
Those transylvanian rugs were undoubtedly made in west central Turkey and the sotheby rug probably in North West Persia.
As for the other rug whose border detail is pictured? Many of the elements used in its design are familiar from kuba rugs but the wool quality and coloration are highly atypical for that area. My guess for its location might be the mythic Surhani designation found in Schurmann's Caucasian Rug book, although this is only a guess.
One thing is for sure, we know little about the fluid transference of designs between Turkey, the Caucasus and NW Persia but one thing we do know: The Trans-Caucasian designation is worthless and needs to be retired asap.