Pope Francis is on his way back from Mongolia this week. On a visit to that country, which has scarcely more Catholics than an outback sheep station, the Pope stood in reverence before a statue of Genghis Khan and later lauded his empire.

The Great Khan had forged a ‘pax Mongolica’ which ‘acknowledged the outstanding qualities of the peoples present in [its] immense territory and put those qualities at the service of a common development’ he said.

Actually, Genghis was the most bloody and brutal warlord of the entire Middle Ages – a man who would have put even Cersei Lannister from...