An international team of archeologists have discovered a massive tomb that belonged to one of ancient Egypt ’s earliest pharaohs. However, the ruler’s identity remains a mystery—as do many details of his long-lost dynasty.

The burial chamber most likely belonged to a ruler in a line of kings once lost to history, researchers said. “It’s a new chapter in investigating this dynasty,” one noted.

Archaeologists have discovered the tomb of an unknown ancient Egyptian pharaoh near Abydos, a historic city in Egypt. The limestone burial chamber, about 23 feet underground, dates back around 3,600 years to a period of unrest known as the Second Intermediate Period.