Under the 5th Dynasty (ca. 2435–2305 BC) the area to the west of the Step Pyramid complex began to be used as a cemetery, where mainly palace officials were buried. Their tombs – in the form of rock-hewn chapels of mastabas built of mud brick – were built between the enclosure wall of the royal funerary complex and the Dry Moat, arranged in North-South rows. With the passing of time, the area became overbuilt and new tombs had to be squeezed between, or they replaced earlier ones. Early in the First Intermediate Period (ca. 2118–1980 BC) this part of the necropolis has been abandoned and no more tombs were built here. Over 40 tombs of officials, dating from the times of 5th and 6th Dynasties, have been identified in the excavated part of the cemetery; these have been presented in detail in volumes I, IV and V of the Saqqara series. Marked on the plan below are the most important ones (click on them to learn more).