Barks' commentaries:

This story of a simple desert outing that turned into a dangerous search for fabulous treasures is sprinkled with real settings and dubious historical ones. The Indian trail where the ducks find arrowheads is real. The 'Lost Ship of the Desert' is questionable, although many old-timers claimed to have seen it.

The plot of Seven Cities of Cibola actually came from local contacts (At the time Barks lived in the San Jacinto area, 120 kilometres east of Los Angeles, California - Editor's remark). My wife, Garé, and I went down to Indio, California, to see Al Koch, the manager of the Riverside County welfare office. He was quite an authority on Indian tribes that had lived around here for generations - their history, the tribal names, the things they did.
He said he would take us to an old Indian trail that went over the top of a mesa out by Thousand Palms. He thought that the Arizona tribes and the tribes on the West coast had used it as a trade route. There was one type of seashell that made beautiful necklaces. The California Indians would carry these shells all the way across the desert, over the Colorado River, and into Arizona, possibly even to Cibola, where these fabled seven cities were. They would trade them there for turquoise and the beautiful things that the Arizona Indians made, then come back. The traffic went on for thousands of years.
Al said: When you see that trail, you'll know that it must have been traveled for thousands of years because you can see the trail in that hard desert soil on top of the mesa, and the Indians had worn it that deep wearing only soft moccasins. So we went up there and looked at the old Indian trail.

Later, he and I had several martinis and got to talking about all the possibilities. The ducks could follow the trail and find the Seven Cities of Cibola. The more we drank the more grandiose the idea seemed. When Garé and I came home that night, I thought of it for a while, and it still seemed very good. But the next morning, when I thought it over, I felt I had only enough for a 10-page story. Just the ducks following an old trail across the desert, and what did they get into? Lizards? I decided I couldn't use rattlesnakes very well. The ducks could get cactus thorns in their feet, they could get thirsty - I was trying to think of things they could do. They could come to the Colorado River and maybe get half-drowned trying to get across. Then they could go into the mountains on the other side. Well, so what? I thought there had to be something more to go in there to fill up the spaces and make it more interesting.

It happened that I was in a restaurant a couple of days later having a hamburger. There was an old hillbilly type of rancher in there. He was telling some guy about the 'Lost Ship of the Desert', a wild legend I'd heard of before. I was really cupping my weak ears to try to hear everything he had to say (Notice that, in the story, the Beagle Boys are doing just that when they hear the ducks talking in a café - Editor's remark). He told of deck railings that were still sticking up. The wood was very well preserved from having been covered with sand. He said it wasn't a very big ship, just a small galleon that could have sailed up the Colorado River. He thought that perhaps a tidal wave had washed it so far in from the sea and that in the four hundred years since then, the river might have changed its course.

It seemed worthwhile to go to the library and see what I could find on that 'Lost Ship of the Desert'. There was evidence that a Spanish expedition did lose a ship up the Colorado and evidence that a great tidal wave had once roared up the river. It was a nice gimmick to have the ducks find this ship and tie it in with the Seven Cities of Cibola by having the bowsprit point right to the cleft in the rocks.

But even with all the material I had assembled up to that time, I still needed something. I needed a menace. The Beagle Boys being in there constantly created suspense and danger. Their finally pulling over the booby trap was just the thing I had to have. So all these elements were the result of walking along an old Indian path and later hearing a long-winded old guy talking in a restaurant. And since Al Koch had suggested the whole idea, I drew him into the 12th page of the story, booting the Beagle Boys out of his office.