The ancient culture known for its contributions to mathematics and astronomy in Mesopotamia is the Sumerians. They are credited with inventing one of the earliest forms of writing, known as cuneiform, and developing a base-60 numeration system that influenced modern measurements of time and angles. The Sumerians also made significant advancements in astronomy, creating early calendars based on lunar cycles. Their contributions laid the groundwork for later civilizations in the region, such as the Babylonians and Assyrians, further advancing mathematical concepts and scientific observations.