The riders gathered in a muddy parking lot in the pouring rain, no one minding the muck or the wet.

The older men with broke-down backs from their bronc-breaking days joked between cigarettes about needing to ride sawhorses. Teenage girls trotted on a couple of mares in need of a stretch. And one of the youngest among them, a 5-year-old from South Dakota, soaked his Converse sneakers in giant puddles as they all waited to begin.

These members of the vast Dakota Sioux diaspora met here on a gray Memorial Day to remember a series of events that occurred 152 years ago: a war, an imprisonment, a mass execution and an expulsion from an ancestral home in Minnesota to the rugged no man’s land of central South Dakota. Some members of this group later left South Dakota for Nebraska.

The full story, which involves broken treaties, unfair dealing and a tidal wave of white immigrants, was not widely known, even among Dakota people who might have heard bits and pieces over the years.

That is one big reason why Jim Hallum organized this weeklong, 180-mile memorial ride from his Santee Reservation in northeast Nebraska to the Crow Creek Reservation in central South Dakota. He wanted to raise awareness of a dark chapter of our shared American history and find healing.