The oldest clay tablets with mathematics date back over 4,000 years ago in Mesopotamia. The oldest written texts on mathematics are Egyptian papyruses. Since these are some of the oldest societies on Earth, it makes sense that they would have been the first to discover the basics of mathematics.
More advanced mathematics can be traced to ancient Greece over 2,500 years ago. Ancient mathematician Pythagoras had questions about the sides of a right triangle. His questioning, research, and testing led to a basic understanding of triangles we still study today, known as the Pythagorean Theorem