I've been reading Hugh Kennedy's "The Great Arab Conquests". It is interesting and readable, but not riviting. He has some cool words like Isohyet, entrepot, and dethesaurization. The 200mm Isohyet line marks where the desert gets more or less than 200mm of rain a year. Entrepot is a place where you sell your product before its final market to save the travel, but loose some profit. A camel train would stop at desert edge and not procede to Paris. And Dethesaurization which means what? It seems to be currency related but I'm at a loss. Any help out there?

Thanks Jerry,
The site you sent me to had this:
[Latin thēsaurus, treasury, from Greek thēsauros.] which ties into the currency idea. The quote from the book is:
They also seized the 'House of Mar [Saint]Daniel' and took the treasure that had been kept there on the orders of the Persian kings since the days of Darious and Cyrus, another example of the dethesaurization of precious metals that so often accompanied the Arabic conquest.