Evidence for his reign has been found in Thebes, where he continued the construction of a turning station for the bark of Amun at Karnak. However, after a year, Achoris reunited Egypt and removed Psammuthis from the throne.
In the fifth century BCE, Egypt was part of the Achaemenid empire. However, in 404, a quarrel started between king Artaxerxes II Mnemonand his younger brother Cyrus, which lasted until 401. The Egyptians, led by Amyrtaeus, seized the opportunity and regained their independence. His reign, however, was unstable, and he was removed from the throne by Nepherites I, the first pharaoh of the twenty-ninth or Mendesian dynasty. When Nepherites died in 392/391, there was a brief crisis of succession. His relative Achoris was crowned as king, but another relative, Psammuthis, was able to expel him briefly. Both men were related to the dead pharaoh, although we do not know how; nor do we what made Psammuthis revolt.