Thanks! This is more outstanding information.
I think there are definitely a few periods in history when the opium trade is well documented and known to be substantial. Obviously, as Chandra shows, the last 2-300 years provide a good example. It's also well established that opium was common in Bronze Age Greece and Egypt.
There are a couple of ways you can extrapolate between these time periods and estimate the significance of the trade at times when there is no known evidence for its existence. At one extreme, you can assume that the trade went dormant for long periods of time and had no influence, or at the other extreme you can assume that it stayed roughly the same throughout the last several thousand years, but operated clandestinely during most of that time.
I think it's reasonable to assume that trade in opium has remained roughly constant and that its influence has always been felt -- but that the evidence throughout most of history has been deliberately concealed. The primary reason for this is well described in Chandra's article ... the business is hugely profitable but it is also ethically compromised. Secrecy is a necessity.
Overcoming this secrecy is what I'm trying to do with the map of trade routes. I'm attempting to use basic principles of economics and detailed information about history and geography to establish a hypothetical framework showing how the trade must have developed. In theory, this will make it easier to determine what the influence of the opium trade may have been at various times and places throughout history.
It's a very speculative approach, but it's also important to remember that the basic premises I'm working with are all known to be true today: the trade is worth the equivalent of 100's of billions of dollars a year, it largely operates in secret, and the primary source points are Afghanistan, Myanmar, and North Korea.
I guess what I'm getting at is that the idea isn't all that radical, it just presents challenges for those who wish to study it. My approach to addressing these challenges may be somewhat unorthodox, but it's also a difficult subject and I think there's a lot to be gained from applying this approach ...