Question: Who is a Greek fabulist and story teller credited with a number of fables now collectively known as "Aesop's Fables" that has a widely used index of  the storyteller who lived in ancient Greece between 620 and 560 BC?
Sentence (from "Aesop"): Although his existence remains unclear and no writings by him survive, numerous tales credited to him were gathered across the centuries and in many languages in a storytelling tradition that continues to this day.
Relevant evidence: No