The "slim Jim" was one of the earliest, dating to the California gold rush. Many a Civil War vet used a G.I. holster with the flap cut off. Wild Bill was known to use a sash as well as holsters. He wasn't into fast draw, as much as deadly accuracy. Only in later times (1880's +) did the "cowboy" rigs that are commonly thought of dominate. Of course, in the Dragoon (horse pistol) era, saddle holsters were still common.
Lots of old tin-types show pistols tucked into belts, but you know they were posed with gallery property! :roll:
As far as cartridge boxes, or whatever, I believe that, if one or two revolvers didn't resolve a fight, THAT'S what the Bowie knife was for! :wink: