The Agate meaning can differ from civilization to civilization.
For example, the Babylonians believed the properties of Agate could be used to dispel evil energy and would place it around their home accordingly. Also, there are some famous Babylonian axe heads that were made out of banded agate dating back before 3000BC.
Persians believed this healing stone could be used to defend against a storm. They did this by burning the agate, which we wouldn't recommend nowadays ;-)
Similarly, while Islamic cultures believed that Agate helped ward off evil eye and tragedies, Egyptians thought the stone helped protect against natural disasters and could deliver powers of speech.
However, the Chinese believed the Agate crystal provided spiritual protection, According to them, the crystal helped make them stay more positive and make space for good luck and fortune.
One of the most famous pieces of agate comes from the Ancient Greek times and is known as the Pylos Combat Agate. Despite being less than one and a half inches wide, it depicts a warrior in hand-to-hand combat. It is said to date back to around 1450 BCE.