Herodotus's account

Most of the life of Cleomenes is known through the Histories of Herodotus, an Athenian historian of the second half of the 5th century. He is one the most important characters of books 5 and 6, covering the decades before the Persian Wars. Herodotus's account however contains many mistakes, especially on the chronology of several major events, and is also very biased against Cleomenes.