In June 2012, US president Barack Obama announced a radical new policy to deal with one of the country’s most vexing problems – the presence of millions of undocumented migrants living in the shadows but constituting a vital part of the American economy.

The subject of immigration has been propelled to the top of the political agenda in the United States with the arrival of Donald Trump, a strident nationalist, in the White House.

High up in the Bolivian Andes, indigenous communities meet in the plaza of Macha and take part in a ritual known as Tinku.