The ancient civilization known for its writing system called cuneiform is Sumer, located in Mesopotamia (modern-day Iraq). Cuneiform emerged around 3400 BCE and was one of the earliest forms of written expression. It involved the use of wedge-shaped marks made on clay tablets using a stylus, allowing for the documentation of various aspects of life, including trade, legal matters, and literature. Sumerians also contributed significantly to mathematics, astronomy, and early governance systems, making them a foundational civilization in human history.