In the 6th century B.C., when the Persians were ruled by the Median kingdom, the founding king of the Persian Empire, Cyrus, who was a mixture of the Medes and the Persians, the recorded story about Cyrus, is that the Median king Astyages dreamed in a sleep that the descendants of his daughter Mandani would seize his throne and become the overlord of Asia. He decided to marry his daughter to Cambyses, a low-ranking and docile Persian prince, in order to disqualify her offspring from Median kingship. But when his daughter was pregnant, the king was awakened by a nightmare: he dreamed that a vine had grown from his daughter's belly, covering all of Asia. As a precaution, the king decided to put his grandson to death as soon as he was born, and the minister in charge of the execution spared Cyrus out of mercy and left him in the care of shepherds.
Cyrus became the leader of a tribe in southern Persia in 559 BCE, and it didn't take long for him to unify the Persian tribes and become the rulers of the Persians, overthrowing the Medes around 550 BC, taking for himself a large area from the Persian Gulf to the Lesser Siade Harith River.
After conquering parts of Asia Minor, Persia became a neighbor of the Lydian kingdom, which at that time included the western half of Asia Minor and the area around the Harris River in the east. Prosperous for its exploitation of gold and as an intermediary on the land route between Mesopotamia and the Aegean Sea**, and in connection with its commercial activities, the Lydians invented metal coinage to act as a medium for the exchange of goods and the payment of services. When Persia expanded to the borders of the country, the reigning king of Lydia was Croesus. Croesus had no trust in Cyrus, the new king of a kingdom, and decided to preemptively strike in 546 BC. According to the Greek historian Herodotus, before sending his troops, Croesus went to the temple of Fairdelphi to inquire about the good and the bad. The oracle replied that if he crossed the Harris River, an empire would be destroyed. The confident Lydians set out in full gear, only to be wiped out by their own country. Croatia was incorporated into the Persian Empire, becoming a province of the empire.
In 539 B.C., Cyrus continued his expansion, attacking Mesopotamia with miraculous speed, conquering Babylon without bloodshed, and thus the entire Neo-Babylonian Empire was incorporated into the Persian territory. Cyrus allowed the Jews imprisoned in Babylon to return to Palestine, establishing semi-independent Jewish vassals, while at the same time granting a considerable degree of self-determination to the other conquered peoples.
In 529 BCE, Cyrus was wounded and died in a conflict between the Kingdom of Persia and the barbarian tribes of the north, leaving behind an unprecedentedly large Persian Empire.