Archaeologists working at the ancient Hatnub Quarry in the Eastern Desert of Egypt have discovered a ramp system that was used to move the large alabaster stone blocks. A central ramp was unearthed with a set of stairs on each side containing post holes. The Egyptians used a sled which was attached by ropes to the wooden poles to carry the quarried stones. These ropes would have acted as a "force multiplier" making it easier to pull the sled and stone blocks up the steep 20% slopes. Researchers have also been studying the multiple inscriptions at the site and have discovered at least two that mention Pharaoh Khufu. This has led them to date the ramp system to at least the Fourth Dynasty in Egyptian history, and suggest that it may have been used in the construction of the Great Pyramid in Giza. Comparing conventional Egyptian chronology with biblical chronology, Pharaoh Khufu's reign in Egypt predated Abraham.