I have a Hamlyn book, edited by Esmond Wright and called 'The Mediaeval and Renaissance World', containing the following immortal paragraph (discussing trade during the Mongol Empire):
The Samarkand market offered rhubarb and silk, and the best silk and galangal came from Peking. The Tibetan rhubarb route was probably more important at this stage than the famous silk road. Very little Chinese silk was in fact imported to the West (where there had been excellent silk factories in Constantinople and Sicily for centuries). Powdered rhubarb was the most drastic purgative known in late medieval Italy and figures among the most expensive items known in household accounts.
The Tibetan Rhubarb Route ! The very name conjures up romance ! Does it end in the infamous Rhubarb Triangle ? I've just got to know more ... but there's little on the web.
Rhubarbinfo has some history, but thinks Rheum Palmatum is the kosher stuff. So does h2g2, BBC's wiki clone and this online herbal. But the species Rheum officinale is known as both Chinese and Tibetan rhubarb. It's the root that was powdered, not the stem.
We know where it came from, but where did it go ?
What route did the Rhubarb Route follow ?
Was it carried in packs, or transported by yak ?
Do you snort powdered rhubarb or swallow ?
So many questions, so few answers. Anyone know ?