Zane Grey did not invent the western but he made it a bestselling novel form, and Riders of the Purple Sage is the book that did it: it stayed in print continuously and outsold almost everything else of its decade. What it fixed for the form was the furniture rather than the plot. The lone rider with a past who arrives to protect somebody who cannot protect themselves, the landscape described at length and treated as a moral force, the valley that can be sealed off, and the violence deferred as long as possible and then decisive. Louis L'Amour worked inside that shape for a hundred books, and Hondo is the purest instance: a man, a dog, a woman alone on a homestead and a landscape that is the real antagonist. The connection is a genre debt with a named founder rather than a borrowing of anything specific, which is what a MEDIUM weight is for.