Archaeologists have unearthed the huge tomb of an unknown pharaoh at an Egyptian necropolis, a team of researchers said on Thursday, in what they are calling the second discovery of a king’s tomb this year.

The team of Egyptian and American archaeologists found the tomb, which the researchers estimate is 3,600 years old, nearly 23 feet underground at Abydos, one of the oldest cities of ancient Egypt. The city, about 300 miles south of Cairo, was a burial place for early pharaohs and became a pilgrimage site in antiquity. A necropolis developed at Anubis Mountain to the city’s south.

Researchers uncovered the tomb at the mountain, at the base of a high desert cliff where strong winds carry gusts of sand. In some places around the necropolis, sand has buried structures more than 16 or 19 feet deep.

The burial chamber features a decorated entryway, several rooms and soaring 16-foot vaults made of mud bricks. It dwarfs a tomb unearthed at Abydos over a decade ago, which was hailed at the time as the first material proof of a “lost” dynasty of kings there.

“It’s a new chapter in investigating this dynasty,” Josef W. Wegner, a curator at the Penn Museum in Philadelphia and the leader of the American side of the excavation, said in an interview on Wednesday. “It’s pretty exciting.”