A lot of 20th century authors probably read many of the dime novels about the American West when they were young. Said dime novels would pre-date TV/Movie westerns by many decades. Same novels were probably sold in Europe and other places during the heyday of the traveling Western Shows of the late 1800s and early 1900s. Obviously much later then the CT or other mentions but the dime novels were likely more widely read. It isn't much of a transition from "2 dust covered drunken cowboys start arguing in the saloon before six shooters are drawn" to "2 dirt covered drunken adventurers start arguing in the tavern before swords are drawn." to start the rather familiar RPG fight in a tavern.