He was the mixed-race son of Owl Woman, daughter of White Thunder (and Tall Woman), a Cheyenne chief and keeper of the Medicine Arrows, and the American William Bent, founder of the trading post named Bent's Fort and a trading partnership with his brothers and Ceran St. Vrain.

Bent was born near present-day La Junta, Colorado, and was reared among both his mother's people, his father and other European Americans at the fort, and other whites from the age of 10 while attending boarding school in St. Louis, Missouri.

Starting in 1870 with the US Indian agent to the Cheyenne and Arapaho, he lived on the reservation in present-day Oklahoma, where he stayed to the end of his life.

She died about 1847, by which time his father had already taken her two younger sisters as secondary wives, in the Cheyenne traditional way of successful men.

He married the 20-year-old Adaline Harvey in 1869, the educated mixed-race daughter of a fur trader friend from Kansas City.

As a member of the 1st Missouri Cavalry Regiment, he fought at the Battle of Pea Ridge in Arkansas, March 6–8, 1862, which was a Union victory.

After his return to St. Louis, which was Union-controlled, he was briefly confined in the Gratiot Street Prison, but was allowed to swear an oath of allegiance to the Union and be released.

This led to four hostages (a young woman and three children) being returned, and to Black Kettle and other Cheyenne chiefs being escorted into Denver to start negotiations with the Governor.

Bent was at Black Kettle's camp of Cheyenne and Arapaho at Sand Creek about 35 miles (56 km) north of Lamar, Colorado, on November 29, 1864.

The Indians in the camp had initiated peace negotiations with the U.S. Army, and believed they were under its protection, but Colonel John Chivington and his force of 700 Colorado volunteers attacked the village.

[5] Bent was among the Indians who fled upstream and found shelter in sandpits dug in the creek bed beneath a high bank.

In January 1865, the young men rode with an Indian army of 1,000 warriors in a successful attack on Julesburg, Colorado, in which they killed many townspeople and soldiers.

On September 8, 1865, the Bents were camped with the Cheyenne at the confluence of the Big and Little Powder Rivers, near present-day Broadus, Montana, when soldiers were sighted only a few miles away.

The soldiers were the Eastern and Central columns of the Powder River Expedition under Colonel Nelson D. Cole, and Brevet Brigadier General Samuel Walker respectively.

Bent lived on the Cheyenne and Arapaho reservation near the town of Colony and worked as a U.S. government employee for most of the rest of his life.

But in 1890, he was the crucial go-between to persuade the Cheyenne and Arapaho to accept plans for allotment of land by individual households under the Dawes Act.

Presented as a way for Indians to assimilate by adopting Euro-American farming styles, the allotment plan caused the loss of considerable tribal land.

Many Cheyenne and Arapaho held Bent responsible for the ill effects of the transition to allotments, including the loss of substantial amounts of tribal lands from the reservation.

In the spring of 1866,[14] he first married Magpie (Mo-he-by-vah;[15] May 10, 1886), a niece (raised as a daughter) of Black Kettle of the Southern Cheyenne tribe.

Daisy gave birth to a child named Smoke Woman and from her lineage came some of the recent and present Chiefs of the Southern Cheyenne.

Eventually, at Bent's recommendation, Hyde became a ghost writer for Grinnell and probably wrote most of The Fighting Cheyennes, published in 1915.