Were the Egyptian pyramids built when the Sahara was already deserted or when it was still green?

 The construction of the Egyptian pyramids, particularly the Great Pyramid of Giza, occurred during a period when the Sahara region was generally drier and more arid than it had been during earlier geological epochs but was not as dry as it is today. The Sahara experienced climatic variations throughout its history, transitioning between more arid and more humid phases.

The construction of the Great Pyramid of Giza is attributed to Pharaoh Khufu, who ruled during the Fourth Dynasty of the Old Kingdom of Egypt around 2580–2560 BCE. During this time, the Sahara region had a more hospitable climate compared to the hyper-arid conditions seen in the present day.

Several thousand years ago, the Sahara experienced what is known as the African Humid Period or Green Sahara, a period of increased rainfall and more favorable environmental conditions. This period roughly spanned from around 10,000 to 5,000 years ago, and during certain phases, the Sahara had lakes, rivers, and vegetation.

However, by the time of the construction of the pyramids, the Sahara was already transitioning to a more arid phase. The construction of the pyramids coincided with a period of reduced rainfall and desertification in the Sahara. While the climate may not have been as extreme as it is today, the region was drier than during the earlier Green Sahara phase.

The ancient Egyptians built the pyramids using limestone and granite quarried locally. They also employed sophisticated engineering techniques for the construction, transportation, and placement of massive stone blocks. The construction of the pyramids is a testament to the organizational and technical prowess of ancient Egyptian civilization, and it occurred during a phase when the Sahara was undergoing a shift toward increased aridity.