NOT based on historic figures
Imdb trivia says so, as do many 10* reviews. People are triggered by the 1* reviews that say not true. The movie just appropriates real people's names.
Nat Love was a cowboy, not an outlaw. He met some outlaws once. Settled down and became a rail porter. Wrote a decent autobiography.
Mary Fields worked for a Ursuline convent in Toledo. After that delivered mail by stagecoach. Never associated with outlaws. She was a big momma who worked and dressed like a man! https://www.nps.gov/people/mary-fields.htm
The Rufus Buck Gang were evil motherfuckers who went a six day crime spree. Were arrested shortly and sentenced to hang. Never got out of jail! https://en.wikipedia.org/wiki/Rufus_Buck_Gang
List of crimes committed by the gang
July 30, 1895: Killing of US Deputy Marshal John Garrett[3]
July 31, 1895: Coming across a white man and his daughter in a wagon, the gang held the man at gunpoint and took the girl.[4]
They killed a black boy and beat Ben Callahan until they mistakenly believed he was dead, then took Callahan's boots, money, and saddle.[4]
Robbing of country stores of West and J. Norrberg at Orket, Oklahoma[4]
Murder of two white women and a 14-year-old girl[4]
August 4: Rape of a Mrs Hassan near Sapulpa, Oklahoma.[5] Hassan and two of three other female victims of the gang—a Miss Ayres and an Indian girl near Sapulpa—also died; a fourth victim, Mrs Wilson, was reported to have recovered; it is reported that, after their capture, the gang was almost lynched[6]