Saudi Arabia has fenced off its border with Iraq. Turkey has constructed a 700-mile concrete wall to separate it from Syria. The Iranian/Pakistan border, all 435 miles of it, is now fenced. In Central Asia, Uzbekistan, despite being landlocked, has closed itself off from its five neighbours.

On the story goes, through the barriers separating Brunei and Malaysia, Pakistan and India, India and Bangladesh and so on around the world. The India/Bangladesh fence is instructive in showing us how the era of wall-building is not just about people in the developing world moving to the industrialised nations. The barrier runs the entire length of the 2,500-mile frontier and is New Delhi’s response to 15 million Bangladeshis moving into the Indian border states this century. This has led to ethnic clashes and many deaths.

Wherever this mass movement of peoples happens at pace it seems to assist a retreat into identity. Almost all recent election results in Europe bear this out. Concurrent is the rise of extremes.