What happened in 561 BC?

In 561 BC, the ancient Greek philosopher and mathematician Pythagoras founded a religious movement known as Pythagoreanism, which emphasized mathematics, philosophy, and a way of life focused on harmony and ethics. This period also saw the rise of various city-states in Greece and the ongoing development of early democratic principles in places like Athens. Additionally, the year is significant in the context of Babylonian history, as it falls within the reign of King Nebuchadnezzar II, who is known for his impressive architectural projects and the Hanging Gardens of Babylon.