A Brief Astrology History- from Mesopotamia to Hellenistic

This piece's content is mainly drawn from American astrologer Chris Brennan’s The Astrology Podcast, specifically the episode The History of Astrology: From Ancient to Modern Times.

Before 2000 BCE, in the region of Mesopotamia, the foundational ideas of astrology began to take shape:

“Heaven and earth are interconnected; when ominous signs appear in the sky, disasters will occur on earth. When disasters happen on Earth, there are also signs to be found in the heavens.”

People recorded celestial phenomena and corresponding earthly events on clay tablets, preserved them in libraries, and passed them down through generations. By around 750 BCE, Mundane Astrology, which served the royal court, had developed in the region. This type of astrology focused on the king, who was seen as a symbol of the nation's fate.

By 500 BCE, astrologers, who were also astronomers, diligently documented and categorized the changes in the sky. The zodiac was standardized into twelve constellations, each spanning thirty degrees. Ephemerides, or tables showing planetary positions, also began to appear around this time, indicating that astrologers were already capable of calculating and predicting the movement of celestial bodies.

In 410 BCE, the personal birth chart finally emerged. Though rudimentary, these charts recorded the positions of celestial bodies at the time of a person’s birth. Astrologers used them to interpret individual destinies. Astrology was no longer confined to serving kings or the state—it began to connect with everyday people.

Another important birthplace of Western astrology was Egypt. Before 2000 BCE, the Egyptians developed a system known as the Decans to determine the timing of their religious rituals. This system divided fixed stars into 36 groups, known as the 36 Decans, and observed their risings and settings in the sky.

The ancient Greek astrological text Salmeschoiniaka recorded how the Decan system corresponded with the houses in later Hellenistic astrology. For example, Decan No. 01 represented the circumstances of a person’s birth; No. 28 signified livelihood; and No. 17 revealed information about marriage.

In the 4th century BCE, Alexander the Great, the son of Philip II of Macedonia, set out from southern Europe with his army, conquering Mesopotamia and Egypt, which were then under Persian rule. These two regions came under the influence of Alexander’s native culture: Greek culture. This historical period is known as the Hellenistic Period.

At the time, Greek became the dominant language (the lingua franca), much like English today. Regardless of one’s native tongue, Greek was used for communication in commerce, science, religion, and philosophy. The impact on astrology was profound. It facilitated the integration of Mesopotamian and Egyptian astrology. By the 3rd century BCE, signs of the Mesopotamian twelve-sign zodiac began appearing in Egyptian temples.

This exchange and cross-pollination among astrologers culminated, by the 1st century BCE, in the emergence of Hellenistic Astrology.