There may be other sources of funding too that are not mentioned in the BBC report.
Taliban collecting taxes to raise funds for ‘jihad’ ** Meagre Zakat and Ushr funds cannot meet militant expenses * ** Abductions for ransom, tax on goods transport among major revenue sources*
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This part is most hilarious "Taliban Collecting Taxes" Collecting Taxes from whom? Northern Alliance for profits made on pushing drugs... LOL....