Complicating the account of this period is the issue of the Peace of Callias, which allegedly ended hostilities between the Greeks and the Persians. The very existence of the treaty is hotly disputed, and its particulars and negotiation are ambiguous. Ernst Badian believes that a peace between Athens and Persia was first ratified in 463 BC (making the Athenian interventions in Egypt and Cyprus violations of the peace), and renegotiated at the conclusion of the campaign in Cyprus, taking force again by 449–448 BC.