Before his accession, Cambyses had briefly served as the governor of northern Babylonia under his father from April 539 BC to December 538 BC. Afterwards, he continued to roam in the Babylonian cities of Babylon and Sippar, before being appointed by his father as co-ruler in 530 BC, who set off to mount an expedition against the Massagetae of Central Asia, where he met his end. Cambyses thus became the sole ruler of the vast Achaemenid Empire, facing no noticeable opposition.