It's a troubling piece of Minnesota's past: Thirty-eight Dakota men hanged from a Mankato gallows in December 1862. Their deaths scarred generations of native people and cemented Minnesota as home to the largest mass execution in U.S. history.

Despite that infamy, if you're a Minnesotan in your 30s or older, it's likely you were never taught about the hangings — or the prairie war between the United States and the Dakota that led to them. Minnesota didn't require students to study that tragic chapter in the state's history.

That past, and how it's taught, surfaced again recently with installation of "Scaffold," a Walker Art Center sculpture built in the shape of a gallows with a reference to the Mankato hangings. It led to an outcry from Dakota community members. While "Scaffold" has been torn down, the controversy has called into question how much Minnesotans know about what happened at Mankato.