A colorful tree-dwelling civilization

I had an extremely detailed dream of which I can unfortunately only remember the general idea. I was looking through a coffee-table book about an imagined civilization whose exact name I can't remember, but it was a four-syllable name beginning with A- and ending in -onhi, and I thought it was clearly intended to sound like something out of the Book of Mormon. The book was full of full-page paintings of this civilization, showing their architecture, mode of dress, etc., together with detailed written descriptions. I took in quite a lot of this detail but again have forgotten most of it. They made extensive use of "flets" -- platforms built high in trees, like those of  Lothlórien in The Lord of the Rings -- but the people did not look at all like Tolkienian Elves. They wore very complicated clothing in bright reds, yellows, and greens, and the overall effect reminded me somewhat of Aztec images such as this one:

The resemblance was only very superficial, though. Overall, I was struck by how original their costumes were. The author had not copied the style of any real-world civilization but had imagined a completely new culture in a level of detail that made it fully convincing. Looking through the book reminded me of how I felt decades ago when I read a list of titles of works by one of Robert Lindner's mental patients:

. . . "The Religious Beliefs of the Valley Dwellers," "Manufacturing Processes and Dye Chemistry," "Fire Worship and Sacrifice on Srom Sodrat II," "Food Distribution in Seranen," "Sex Habits and Practices of the Crystopeds, "Plant Biology and Genetic Science of Srom Olma I," and so on . . .

I wanted to read them all, and I resented Dr. Lindner for just giving us the titles and nothing else. I felt the same way in the dream. I was absolutely fascinated by this imagined civilization and wanted to read all about it.

Later in the dream, an archaeologist was showing me some recently discovered stone tablets, and he said that all the information in the book I had been looking through came from these tablets. I was astonished: "Wait, you mean it's real?"

Hundreds of these tablets had been found. Each was about a foot and a half square and two or three inches thick and was engraved on one side only. They had been used as roofing tiles on several ancient buildings, and only recently had archaeologists discovered that there was text engraved on the undersides of these tiles, which could only be seen by removing them from the roof. The text had been deciphered, and it surprisingly turned out not to deal with historical or mythological events but rather to give a very detailed description of every aspect of the culture that had created them. Again, I wanted to read it all, but unfortunately I soon woke up and found my memory of the details rapidly evaporating.