For decades afterwards, the online drugs trade was severely constrained by the ability of law enforcement to track IP addresses and the means of payment.
The trickle of transactions threatened to become a flood with the emergence a few years ago of Silk Road, a drug-dealing site on the "dark net". These e-depths cannot be reached through a normal browser but only with anonymising software called Tor. Buyers and sellers transact there pseudonymously in bitcoin, a crypto-currency.
Silk Road was shut last year with the arrest of Ross Ulbricht, the 29-year-old American whom investigators believe to be Dread Pirate Roberts, the site's founder. Mr Ulbricht is due to stand trial in New York next January on charges that include computer hacking and money laundering.
But law enforcers who predicted that Silk Road's demise would mark the beginning of the end for online black-market bazaars were wrong. Instead, dozens of dark-net Amazons and eBays (also known as crypto-markets) have sprung up to fill the void. They are not only proving remarkably resilient but expanding their offerings and growing more sophisticated.