Ancient Mesopotamia is considered to be the oldest civilization. It emerged in the region of present-day Iraq, Syria, and Kuwait around 3500 BC and lasted until around 500 BC. The Sumerians, who were the first people to settle in Mesopotamia, developed a complex society with advanced farming techniques, writing, and architecture. They built the first cities, including Uruk and Ur, which were among the largest and most advanced in the ancient world. The Sumerians were also skilled in astronomy, mathematics, and medicine.