Explain what exactly? Sorry, but I simply cannot understand what you're asking me to explain.
Further, let me get this straight. You want to say, after linking to that page, that the Taliban eliminated it when they could. This then implies that you're saying that they were against it before that banning, but could only actively take a stand against it in 2000?
Did you then skip the section directly above the one you're quoting? You know, the one which states, during the Warlord Period, 1989-1994, "various Mujahideen factions started fighting against each other for power. With the discontinuation of Western support, they resorted ever more to poppy cultivation to finance their military existence." The Mujahideen, if you didn't know, would go on to become, drum roll please, The Taliban!
So the Taliban, before they were even called that, resorted to poppy cultivation to finance their military existence in 1989. You just quoted that exact paragraph from Wikipedia, so you can't deny this. Do you know how Opium is made? Here's a hint. It's made from drying poppies. As is heroin.
And then in the same paragraph you quoted, is the line, "During the Taliban rule, Afghanistan saw a bumper opium crop of 4,500 metric tons in 1999". Gee, I wonder if these Mujahideen, who became the Taliban, who were relying upon farming poppies, which is what you use to create Opium and Heroin, might have had a hand in the bumper crop of opium under their rule.
Or do you think it was just a total coincidence that this group who were growing poppies in order to fund their military existence also just happened to start running a country which saw record breaking levels of opium production?
So please, tell me in detail, what you're finding hard to understand here. You're saying that the Taliban outlawed the production of Opium. You then went ahead and quoted the paragraph from Wikipedia which says the exact opposite. What are you trying to argue here?