The term Golden Age referred to two different great periods in history both on Earth and Bajor.
In 2267, the crew of the USS Enterprise discovered that the myth of the Golden Age originated from a race who visited the Mediterranean region of Earth around 2700 BC. Due to their psychokinetic abilities, they became known as the Greek gods. Greek civilization and consequently, much of later Human culture and philosophy derived from the worship of these beings. (TOS: "Who Mourns for Adonais?")