Modern paper money isn't made of paper - it's made of cotton fibres or plastic. And the Chinese money that so fascinated Marco Polo wasn't quite paper either. It was made from a black sheet derived from the bark of mulberry trees, signed by multiple officials and, with a seal smothered in bright red vermillion, authenticated by the Chinese emperor Kublai Khan himself.

Russian President Vladimir Putin has had a good run over the past few months. Edward Snowden, the former NSA contractor, landed on his doorstep, a gift from the PR gods. Agreement on Syria went from no chance to golden opportunity in the course of one afternoon. Forbes dubbed Putin the most powerful man in the world. Yet all these successes obscure a basic fact: Russia is running out of money.

Abukar Abdulle Mohamed is a busy man. His three phones keep beeping away as he negotiates and shakes hands with a group of mainly middle-aged men. Fifty-four-year-old Mohamed is a livestock trader with more than thirty years experience and has just sold his tenth goat of the day at Hawl Wadaag livestock market in Mogadishu. But he isn’t holding wads of cash in his hands to show for the day’s sales.