Though boomerangs are iconically associated with Australian Aboriginal peoples, it's difficult to know exactly when and where this tool originated. Ancient humans used boomerangs for thousands of years before the advent of more modern tools. The oldest-known boomerang is thought to be about 20,000 years old and was actually found in Poland.
The term "boomerang" applies to a wider variety of tools than most people might realize. The Polish boomerang is a non-returning boomerang; the returning kind are thought to have originated in Australia. From this perspective, it can be said that boomerangs as most people know them were likely invented about 10,000 years ago by Aboriginal people in what is now known as Australia.