Literary detectives suspect that an earlier, lost edition of Amadís de Gaula existed.
[The Golden Tower of Seville, part of the city defenses constructed in 1220 by the Moors. A twin tower stood at the other side of the Guadalquivir River, and thick chain between them controlled ship traffic for the port. Trade with the New World made Seville one of the richest cities of Europe. Photo by Sue Burke.]
The earliest surviving copy of Amadís de Gaula was printed in 1508 in Zaragoza. (Here's my commentary on that handsome tome.) But it might not be the first time Amadís appeared in print.
Juan Manuel Cacho Blueca, one of Spain's top Amadis scholars, believes that Garci Rodríguez de Montalvo may have started rewriting medieval manuscripts of Amadís before 1492, the year the war of Reconquest ended in Granada, and probably finished it and the sequel about Amadis's son, Sergas de Espandian (Exploits of Espandian), between 1495 to 1497. He believes that because comments in Sergas seem to relate to events during those years in the real world.
Other scholars date the completion even earlier, although the prologue for Books I, II, and III in the novel could only have been written between the end of the war and the death of Queen Isabel I in 1504 due to specific references its content. Likewise, Book IV and Sergas, which Rodríguez de Montalvo composed himself instead of rewriting existing works, must have been finished before the prologue was written, too. He probably died before 1505; we don't know much about his life.
In any case, in the late 1400s, novels of chivalry were an established popular genre. The printing press had spread fast throughout Europe. Some German printers brought their mastery of that new technology to Spain, at the time a leading world power, in search of steady work. This is why Spain's earliest printers include names like Cromberger and Hagembach.
Specifically, Meinardo Ungut and Stanilao Polono seem to be the most likely suspects to have printed Amadís de Gaula in Seville in 1496 or later, when they had a shop in that city, which at the time was a bustling seaport. In those days, a book was composed either from a manuscript or from an existing book. Small but consistent differences in spelling and grammar show that some of the editions of Amadís in the early 1500s were composed using a different version from the 1508 one — apparently the missing 1496-or-later edition.
A book published before 1501 is called an "incunabulum," from the Latin word for "swaddling clothes" or "cradle." Few of these tender infant tomes have survived. Many other books besides Amadís have lost first editions, and in fact editions of Amadís printed in Seville in 1511 and Toledo in 1524 have no surviving copies.
In the end, history gives us frustratingly few facts and precious few artifacts — and plenty of speculation and controversy. Rodríguez de Montalvo's version of Amadís de Gaula probably wasn't first published in 1508. But no one sure.