In ancient Egyptian history, the Old Kingdom is the period spanning c. 2700 – c. 2200 BC. It is also known as the "Age of the Pyramids" or the "Age of the Pyramid Builders", as it encompasses the reigns of the great pyramid-builders of the Fourth Dynasty, such as King Sneferu, under whom the art of pyramid-building was perfected, and the kings Khufu, Khafre and Menkaure, who commissioned the construction of the pyramids at Giza. Egypt attained its first sustained peak of civilization during the Old Kingdom, the first of three so-called "Kingdom" periods, which mark the high points of civilization in the lower Nile Valley.