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.

A 2014 excavation proved the Abydos Dynasty existed. Now, Archaeologists have found a second tomb, but the king's identity remains unknown.

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. The tomb was found at the Anubis Mountain necropolis by experts from the University of Pennsylvania Museum and Egyptian archaeologists.