context: The Chronicle reports that Askold and Dir continued to Constantinople with a navy to attack the city in 863–66, catching the Byzantines by surprise and ravaging the surrounding area, though other accounts date the attack in 860. Patriarch Photius vividly describes the "universal" devastation of the suburbs and nearby islands, and another account further details the destruction and slaughter of the invasion. The Rus' turned back before attacking the city itself, due either to a storm dispersing their boats, the return of the Emperor, or in a later account, due to a miracle after a ceremonial appeal by the Patriarch and the Emperor to the Virgin. The attack was the first encounter between the Rus' and Byzantines and led the Patriarch to send missionaries north to engage and attempt to convert the Rus' and the Slavs.
question: ఆస్కోల్డ్, డిర్ ఏ సంవత్సరాలపాటు కీవ్ మీద దాడిచేశారు?
answers: 863–66