Ancient Egyptians worshiped Apis bulls as manifestations, or heralds, of Ptah, the creator-god of Memphis, 15 miles south of modern Cairo. The Apis cult stretches back to the earliest dynasties, and the bulls themselves were associated with the pharaoh. Only one Apis bull at a time was chosen to preside over the cult; when that bull died, there was national mourning, the embalmed bull was transported in procession from Memphis to nearby Saqqara, where it was buried in underground catacombs known as the Serapeum, and a new bull was chosen.

In 1850 the French archaeologist Auguste Mariette discovered the Serapeum at Saqqara. The catacombs contained mummified bulls, massive stone sarcophagi (such as the one shown) and—especially important for chronologists—inscribed stelae dedicated by high priests at the death of each Apis bull.

Many of the inscriptions include the names of the pharaohs who ruled during an Apis bull’s lifetime, as well as the bull’s birth date, death date and life-span. These texts have enabled scholars to date securely the reigns of Egyptian pharaohs—and any other rulers with whom those pharaohs were in contact—back to 664 B.C.

Following is a quotation from the earliest inscription found in the Serapeum. It tells us that the Nubian pharaoh Taharqa (c. 690–664 B.C.) preceded the pharaoh Psamtik I (664/663–610 B.C.) and that the bull died at the end of Psamtik’s 20th regnal year:

“Year 20, fourth month of the third season (twelfth month), day 21; under the majesty of the King of Upper and Lower Egypt, Wahibre; Son of Re, of his body, Psamtik I; went forth the majesty of Apis, the Living Son, to heaven.

“This god was conducted in peace to the Beautiful West in the year 21, second month of the first season (second month) (on) the twenty-fifth day.

“Now, he was born in the year 26 of King Taharka; he was received into Memphis on the fourth month of the second season (eighth month), (on) the ninth day; which makes it 21 years.”