"Una canción campesina." With these words, the artist and songwriter known as Compay Segundo describes the source from which he drew the inspiration for "Chan Chan." Which I understand to mean, not a tale or story, but a "traditional song from the countryside."

Then there are these words:
"dos personajes de mil ochociento." My translation is, Two characters from the years of the 1800's.

So if you put those two together, what you have for Compay Segundo's source material is: a traditional song lyric, with a setting from an earlier century, from the 19th century sometime. That does not limit the song to the 19th century, it seems to me; the song could be a more recent traditional song, with a nostalgic recollection of an earlier era.   

It may also be noted that the municipality of Santiago de Cuba, on the eastern part of the island, was the capitol city in the 1500's before the government of the island was relocated to Habana. So this is a region whose traditions go back well into the earliest colonial centuries.