Don Rodriguez; Chronicles of Shadow Valley by Lord Dunsany

After long and patient research I am still unable to give to the reader of these Chronicles the exact date of the times that they tell of. Were it merely a matter of history there could be no doubts about the period; but where magic is concerned, to however slight an extent, there must always be some element of mystery, arising partly out of ignorance and partly from the compulsion of those oaths by which magic protects its precincts from the tiptoe of curiosity.