550 BCE
Cyrus the Great defeated the Median king Astyages and founded the Persian Achaemenid Empire, which would grow to become the largest empire the world had yet seen, stretching from Egypt to Central Asia.
Civilization & Governance
- Cyrus II of Persia, later known as Cyrus the Great, defeated his overlord Astyages of Media and united the Persian and Median kingdoms, founding the Achaemenid Empire.
- Cyrus embarked on a series of conquests that would eventually bring Lydia, the Greek cities of Ionia, and the Neo-Babylonian Empire under Persian control, creating the largest empire in history to that date.
- The Achaemenid Empire adopted a policy of relative tolerance toward conquered peoples, allowing subject populations to maintain their customs, religions, and local governance under Persian oversight.
Culture & Society
- Greek philosophy was flourishing in Ionia, with thinkers such as Anaximander and Anaximenes developing naturalistic explanations for the origins and structure of the physical world.
- The Buddha, Siddhartha Gautama, was active in northern India during this approximate period, developing the teachings that would become the foundation of Buddhism.
Climate & Environment
- Atmospheric carbon dioxide concentration was approximately 280 parts per million, as later confirmed by ice core analysis.
- The world population was approximately 135 million.