Afghan police recently found a stash of 2,000 shells, mines, rockets and grenades in the north. Much of it was left over from the 1980s, when the Soviets were trying to prop up a communist government in the face of a tribal uprising. Tribes, warlords or individual farmers or herders still own lots of this stuff, and they are waiting for a buyer. Few of the people who possess there old munitions have any use for it, or, often, even a weapon that can fire it. But Afghanistan is a poor country, and if you find something useful, you keep it. Now there is a market for these old munitions. The Taliban is carrying out a roadside bomb campaign against the Afghan army and foreign troops. Often they have to used homemade fertilizer (ammonium nitrate) explosives. But military grade explosives, even if thirty years old, are preferred. The old junk has turned to gold.
There are believed to be thousands of tons of these old munitions hidden throughout the country. The ammo was either given to various tribes that sided with the Russians, or looted from army depots when the communist government, which the Russians abandoned in 1989, finally collapsed in 1993. Many of the old shells and mines tend to be hidden away in cellars or caves. This slowed the chemical reactions, taking place in propellants and explosives, decades after these items were manufactured. Eventually, the compounds, that make the propellants and explosives work, break down. This renders the propellants and explosives useless or, in some cases, unstable and very dangerous.
Most of the old ammo in the south has already been found, or used. So the Taliban, and the government, are seeking out the old stashes up north. While the Taliban will pay, the government just takes it or (after giving any tipsters a reward), and, more often, blows it up in place, if it is out in the countryside. This stuff is dangerous to use, and often the cause of explosive accidents terrorists have while turning shells into roadside bombs.