Greek mythology is not a religion, in the sense we use the world religion today. However, it was a part of the religion and religious beliefs of ancient Greece. Greek mythology is a collection of myths told by the ancient Greeks and which deal with the numerous Greek gods, mythological creatures, and heroes of ancient Greece.
Even thought it was always assumed that mythological stories are not real, in recent years many scholars tend to believe that many elements of Greek mythology have strong factual and historical roots.
Over the years, Greek mythology has changed to accommodate the evolution of the Greek culture. The earlier inhabitants of the Greek mainland and islands were an agricultural people who, using Animism, assigned a spirit to every aspect of nature. Eventually, these spirits assumed human forms and entered the local mythology as gods, demigods or other mythological creatures. When tribes from the north (Dorians) invaded mainland Greece, they brought with them a new pantheon of gods, based on conquest, force, prowess in battle, and violent heroism. Other older gods of the agricultural world fused with those of the more powerful invaders or else faded into insignificance.
Epic poetry created story-cycles and, as a result, developed a new sense of mythological chronology. Greek mythology then unfolds as a phase in the development of the world and of human beings. While several contradictions in these mythological stories make a proper commonly accepted timeline impossible, an approximate chronology can be recognized.
The mythological “history of the Greek world” can be divided into three periods: