The Fictional Date?

Major Twist, one of the characters, also narrates the movie.

At the beginning he says it began on a warm summer day in 1854. Chief Conquering Bear is brought home to die after a battle with the soldiers, and utters a prophecy about a future great leader of the Sioux, which a little boy named Crazy Horse hopes and fears he might be.

Conquering Bear was fatally wounded on August 19, 1854 when a minor dispute escalated into the Grattan Massacre, and died 9 days later.

The narrator says that many years pass and Crazy Horse grows into a strong warrior as the US Civil War (1861-65) begins and ends. In what seems to be a single fictional year Crazy Horse marries Black Shawl (1871 in real life), gold is found in the Black Hills and the Black Hills gold rush starts (1874 in real life), Fort Phil Kearney is built (1866), the Fetterman Massacre happens (December 21, 1866), the Treaty of Fort Laramie is signed (April-November, 1868), Crazy Horse’s daughter is born (1873 or earlier) The Battle of the Rosebud is fought (June 17, 1876) Crazy Horse’s daughter dies (1873), the Battle of the Little Bighorn is fought (June 25 1876), and the great Sioux camp disperses into smaller camps to gather food for the winter.

In the next fictional year, a bitter winter causes all the Sioux bands to come into the reservation one by one. Crazy Horse’s band is the last to do so, except for Sitting Bull’s followers in Canada. Crazy Horse makes peace while it is still winter (May 5, 1877 in real history). Spring and summer come. The death of Crazy Horse according to the prophecy (September 5, 1877 in real history).

Victor Mature (January 29, 1913-August 4, 1999) plays the mature Crazy Horse, and so was 41 or 42 when Chief Crazy Horse was filmed, thus putting the fictional date of Mature's scenes about 29 to 34 years after 1854 if the boy who played child Crazy Horse was 8 to 12 years old. According to this logic the events of mature Crazy Horse should happen about 1883 to 1888.

So are the the events of the mature Crazy Horse's life supposed to happen about 1866-67 based on the Fetterman Massacre, or 1876-77 based on the Great Sioux War of 1876-77, or in the 1880s based on Mature's maturity?

Is there a time skip between the 1860s and 1870s? Major Twist is wounded (for the 2nd time in the movie) about 1868 in history and is too weak to travel until what is historically 1877. Did it take Twist only a few months of fictional time to heal? Did it take him 8 years to heal? Was he wounded a third time off screen sometime about 1876?

Or does the fictional history of Chief Crazy Horse (1955) have duplicates of the Fetterman Massacre, and/or the Battle of the Rosebud, and/or Custer's Last Stand, so that at least one duplicate battle happens in the same year as at least one historical battle?

Possible theories are:

1) Events happen in 1866-68 and then after a time skip in 1876-77.

2) All events happen in 1866-68 including duplicate Rosebud and Little Bighorn.

3) All events happen in 1876-77 including duplicate Fetterman Massacre.

4) All events happen in 1880s including duplicate Fetterman Massacre, Battle of the Rosebud, & Little Bighorn. This might be part of the same non historical Wild West war as the one in The Savage (1952). https://moviechat.org/tt0045123/The-Savage/5d0d59193e04835683e40cc0/The-Date?reply=5d11966b545b030d3b66e885