Mimicking the hills that surround the village, hundreds of earth lodges occupied On-A-Slant. Dustin White photo.

Dustin White
Editor

Two hundred years before the United States would be formed, families from three villages decided to come together to build a fortified village. The purpose of the new village was twofold. First, it provided defense, as it was protected largely by natural formations. Second, it provided access to quality farm land near the Missouri River. This village was called, “Miti-o-pa-resh,” the slanting village. Locals know it as On-a-Slant.

The history of On-a-Slant goes back much further though, with the migration of the Nu’Eta, which means “The People.” Later, this tribe would be known as the Mandan. 

Tracing the history of the Mandan Indians is relatively difficult. Having passed down their history orally for centuries, when a majority of the tribe was wiped out during a smallpox epidemic, much of their history also was lost. 

Believed to have originated in the Ohio River Valley, the Mandan Indians migrated north, along a path that generally paralleled the Missouri River. 

In 900 C.E., they had reached the plains of South Dakota. Being farmers, they began settling near the river. Continuing to move north, it is believed that they settled at least 130 villages. Scholars believe at any one point, only about 10% would have been inhabited though. 

When the Mandan arrived at the Heart River, they would eventually build nine villages along the Missouri. Two of the villages were constructed on the east side, while the remaining seven were on the west side. 

On-a-Slant village, which was built around 1575, was one of the southernmost of the nine villages, having been located near the mouth of the Heart River, which the Mandan Indians believed to be the center of the universe. 



Over the next couple hundred years, the nine villages would thrive, reaching a population between 10,000-15,000 people. On-a-Slant, which consisted of approximately 86 earth lodges, is thought to have supported a tenth of that population. 

It was the women who were responsible for the earth lodges. Learning at an early age as to how to build the lodges, the women would set out to construct the large structures which would serve as the homes to 10-15 members of a family. 

As unique sedentary communities among the Plains Indians, it didn’t take much time until the Mandan villages became centers of trade, and in turn, were central in the inter-tribal trade network. Having the ability to grow a surplus of food gave the Mandan the added advantage of being able to trade those goods. 

Being located along the “highways” of that time, the villages saw a good deal of traffic moving through them, which eventually would be a cause of their downfall. 

As Europeans continued to move westward, they learned of the hospitality of the Mandan. Providing friendly trading partners, the contact at first was peaceful. 

Tragedy
While trading remained generally peaceful, tragedy eventually struck. As with many other American Indian tribes, the Mandan fell victim to the smallpox epidemic of 1781. The epidemic swept from Mexico to Canada, and from the Mississippi to the Pacific coast, leaving devastation in its path. 

On-a-Slant suffered greatly, with a majority of their population having been lost. Throughout the nine villages of the Mandan’s, the same was true, killing nearly 80% of the Mandan, and forcing the rest from their villages. 

The last chief of On-a-Slant, Good Boy, rallied the survivors, and along with others who survived in nearby villages, once again moved north, and established a city near their Hidatsa allies. 

Just over two decades later, in 1804, Lewis and Clark would come upon the abandoned village. By then, the village was already falling into disrepair. The once mighty village was decaying quickly, with heaps of earth having already fallen from the earth lodges. 

The next few decades would seal the fate of the Mandan. Struggling against additional epidemics of smallpox, and trying to defend themselves against other warring tribes, the few Mandan who had survived the devastation of 1781, were dwindling down. 



When the smallpox epidemic of 1837 struck, the Mandan were once again devastated. Having once been a powerful tribe of over 10,000 people, they were reduced to around 125. 

Just over a hundred years later, in 1971, the last full-blooded Mandan Indian, Mrs. Mattie Grinnell, who was 108 years old, is said to have died. 

Rebuilding
After the Mandan abandoned On-a-Slant village, nature began to retake the land. Fort McKeen, and then Fort Abraham Lincoln would be set up near what once was a central trade hub. 

It wouldn’t be until after the demise of Fort Abraham Lincoln that attention would once again be given to On-a-Slant. With the nation falling into a depression, the Civilian Conservation Corps would set out to work in 1934. 

Enlisting Scattered Corn, a Mandan Woman who had learned the technique of building earth lodges when she was just a young girl, the CCC began rebuilding at part of the village that was in ruins. 

Rising out of the murkiness of the past, On-a-Slant once again sprung to life, introducing new generations to a history that could have been forgotten. 

In all, On-a-Slant village lasted around 230 years, while the Mandan society around the Heart River had an even longer history. 

As our state just recently celebrated 125 years, it is worth remembering those civilizations that flourished before us.