I spent this summer conducting research up and down Greenland’s scenic west coast. Along the way, it wasn’t the snowy mountains or sapphire fjords that caught my eye, but rather the flags. Red and white Greenlandic flags adorned boats, houses, trampolines, jackets, sweaters, caps. Grocery store aisles were draped in bunting. The message was clear even to people like me who don’t speak Greenlandic: Greenlanders are proud of their identity and autonomy. They should be; it’s been hard won.

The prospect of the island’s sale this past week to the United States was rightly understood — by everyone except the president at least — as a joke, though not a particularly good one. What’s been less well understood is how President Trump’s idle musing has added another chapter to the long history of Greenland and its people being viewed simply as a resource to be exploited by larger powers. That underlying attitude is still very much present today.

Modern Danish colonization of Greenland began with what today might also seem like a joke. In 1721 the Dano-Norwegian missionary Hans Egede persuaded the Danish king and private merchants to fund an expedition to Greenland: He wanted to search for lost Vikings who hadn’t yet been converted to Protestantism.