The tropical Ages follow a pattern resulting from the Modality of the 3 Signs of each seasonal Age-quadrant. The Cardinal-sign Ages are innovative, and create a new theme; then, the Fixed establish and intensify the innovations; and, the Mutables are about versatility and variations.
The Modality interacts with the clash between the Individualistic foreground, and the Traditionalism of the background Ages, which are concurrent; and, that's what causes this pattern:
The true nature of the foreground Age (which I refer to as "the Age") of a Cardinal-sign, is held back strongly by the Traditionalism of the Mutable-sign background Age, which is of the previous quadrant of Ages. For this Capricornian Age, the Dark Ages were a result of the changeover from the tropical Age of Sagittarius into Capricorn, with traditional precepts still dominating. In the middle period, known as the Renaissance, the foreground Age was able to begin asserting itself, and then became increasingly dominant in the last Decant, which included the Industrial Revolution and the development of materialistic science, and especially the rise of individualism, which is the Modern period.
For a Fixed-sign Age, such as the one coming up next, the dominance of the Individualistic foreground Age will occur immediately, since Traditionalism itself, instead of interfering, will allow something new to develop right away. So, a quick start for the true nature and full impact of the Fixed-sign of of Aquarius.
The Mutable-sign Ages get the middle period for strongest influence. For the Age of Sagittarius, that was the Greek Classical era.
The First Dynasty of Ancient Egypt occurred at the very beginning of the Fixed-sign, tropical Age of Scorpio, immediately following the innovations occurring at the end of the Cardinal-sign Age of Libra, which started the theme of city-state civilization in the Tigris-Euphrates region. The new theme, already in progress at the end of this Cardinal-sign Age, is globalization, whereas the theme of the previous quadrant of Ages was localization.