This episode occurs in 1875, based on the dates of death on the tombstones of Bert Talman's victims.
Even though the headstones on grave say 1875, the time line has to be after June 1876 because 2 shows before Paladin was at the Little Big Horn right after the 7th Calvary was wiped out. Therefore the graves cant be recent, they have to at least 7 months old.