In some parts of the Muslim world, men wear extremely baggy trousers, which is rationalised in terms of an old legend that Muhammed will come to the world again, and this time will be born to a man, not to woman. The extra space is tio catch the baby, in case there is a lack of advance warning. This applies in Bulgaria and other Eastern Mediterranean parts. Now whether this is true in Afghanistan I dont know, but it might be the explanation of how these vast amounts of soil were transported.