Possibly the AS who helped the Jenn Aiel build Rhuidean put a similar sort of ward around the city, though not necessarily an actual dreamspike. My guess they warded it from T'A'R to keep the objects there safe from prying eyes and what not until the AS reclaimed them, among other things. It would seem though that the AS who went on to found the WT may have forgotten that the Aiel were tasked with keeping the items safe.