It's no accident that most of the Taliban violence in Afghanistan is taking place in, or near, Helmand province. Just west of Kandahar province, the core of the pro-Taliban tribes, 42 percent of the poppy crop comes from Helmand, and 65 percent comes from Helmand, and adjacent provinces. At the farmers level, the poppy crop is worth about $750 million (that's some ten percent of GDP) a year. The total value of the drug trade in Afghanistan is about $2.5 billion a year. This is big money, and it is obtained by tribes working with drug gangs. In some cases, the tribes ARE the drug gang, with heroin production becoming a very lucrative enterprise which benefits most members of the tribe. Thus when the government comes in and says they want to eliminate poppy cultivation, and the Taliban come along and offer to protect it, what's an upwardly mobile tribesman to do?
There is a downside for the tribes. Some 200,000 Afghans have become addicted to opium (the first product refined from poppies, and the raw material for heroin) and heroin. That's nearly one percent of the population. About three-quarters of the addicts use the cheaper opium. The addiction problem will only get worse. There are already some five million addicts in neighboring Pakistan and Iran, that's more than twice as many, per capita, as Afghanistan. Those two countries have, over the past two decades, pushed the drug production business out, and into Afghanistan. As a practical matter, Afghanistan could try to push the drug trade north, into the Central Asian states. You can't come out and say that publicly, but neither did Pakistan and Iran announce the fact that they were looking the other way as their drug production fled into neighboring Afghanistan. The sad fact is, there will always be a market for this stuff, and the farmers in this part of the world make, for them, enormous amounts of money (three, or more, times what they make on growing grain) by cultivating poppies. If you want to see the future of this sort of think, look at South American countries where coca (the raw material for cocaine) is grown. The drug financed rebels can last for decades.