The world has entered a new age of mass migration

If all the people who live outside the country of their birth united to form their own — a republic of the rootless — it would be the fifth-largest country in the world, with a population of more than 240m people, writes Mark Leonard 

Though much has been written about how a world on the move is changing national politics, there has been little consideration of its geopolitical effects. But the mass movement of people is already creating three types of migration superpowers: new colonialists, integrators, and go-betweens.

The new colonialists call to mind the settlers from Europe who spread across the world in the 18th and 19th centuries, benefiting not just themselves, but also their homelands. Similarly, the most mobile populations of the 21st century are helping their countries of origin obtain access to markets, technology, and a political voice in the world.