Archaeologists excavating in the city of Lahoun in the Fayoum oasis (the same area where the hoard of Ptolemaic coins was found last month) have uncovered an underground labyrinth containing 57 tombs from different periods, 45 of them complete with coffins, sarcophagus and mummies inside. (NB: The ABC News story erroneously reports the total number of tombs as 45, but it gives the best overview so I decided to link to it anyway.)

The breadth of this find is astonishing. There were 12 wooden sarcophagi stacked inside an 18th dynasty (1550 to 1292 B.C.) tomb, each of them still containing mummies. The sarcophagi are made out of cartonnage, layered plaster and papyrus that forms a hard covering for a body or face mask, and richly decorated with incantations from the Book of the Dead and scenes of the deities.

But the most surprising finds upend what archaeologists knew previously about the site:

But the most significant findings were 14 tombs, all from the second dynasty. [Lead archaeologist Abdel Rahman] El-Aydi explained to ABC News that one of the tombs was found intact inside. “We found a coffin of the deceased, a wooden coffin of the type known as a house coffin, because it has the shape of the palace or house facade of this period.”

Inside this coffin the deceased was placed in a twisted position and covered in huge amounts of linen, not rags, because in that dynasty ancient Egyptians had no knowledge of the mummification process, El-Aydi said.

Other coffins were found placed in the southwest corner of this one tomb, and on the floor toward the east side was funeral furniture, consisting of huge cylindrical alabaster jars, a wooden headrest and a polished wooden offering table.

Before this find, archaeologists believed the site dated to the reign of 12th dynasty King Senwosret, but the 2nd dynasty tombs are a full thousand years older than that, from around 2750 B.C.

The team will continue excavating, cataloging and recording the site until June, then will move the finds to museums and storage facilities.