Crimea as well. At Sarkel he established a Rus' settlement called Belaya Vyezha ("the white tower" or "the white fortress", the East Slavic translation for "Sarkel"). He subsequently destroyed the Khazar capital of Atil. A visitor to Atil wrote soon after Sviatoslav's campaign: "The Rus' attacked, and no grape or raisin remained, not a leaf on a branch." The exact chronology of his Khazar campaign is uncertain and disputed; for example, Mikhail Artamonov and David Christian proposed that the sack of Sarkel came after the destruction of Atil. Although Ibn Haukal reports the sack of Samandar by Sviatoslav, the Rus' leader did not bother to occupy the Khazar heartlands north of the Caucasus Mountains permanently. On his way back to Kiev, Sviatoslav chose to strike against the Ossetians and force them into subservience. Therefore, Khazar successor statelets continued their precarious existence in the region. The destruction of Khazar imperial power paved the way for Kievan Rus' to dominate north–south trade routes through the steppe and across the Black Sea, routes that formerly had been a major source of revenue for the Khazars. Moreover, Sviatoslav's campaigns led to increased Slavic settlement in the region of the Saltovo-Mayaki culture, greatly changing the demographics and culture of the transitional area between the forest and the steppe. Campaigns in the Balkans The annihilation of Khazaria was undertaken against the background of the Rus'-Byzantine alliance, concluded in the wake of Igor's Byzantine campaign in 944. Close military ties between the Rus' and Byzantium are illustrated by the fact, reported by John Skylitzes, that a Rus' detachment accompanied Byzantine Emperor Nikephoros Phokas in his victorious naval expedition to Crete. In 967 or 968, Nikephoros sent his agent, Kalokyros, to persuade Sviatoslav to assist the Byzantines in a war against Bulgaria. Sviatoslav was paid 15,000 pounds of gold and set sail with an army of 60,000 men, including thousands of Pecheneg mercenaries. Sviatoslav defeated the Bulgarian ruler Boris II and proceeded to occupy the whole of northern Bulgaria. Meanwhile, the Byzantines bribed the Pechenegs to attack and besiege Kiev, where Olga stayed with Sviatoslav's son Vladimir. The siege was relieved by the druzhina of Pretich, and immediately following the Pecheneg retreat, Olga sent a reproachful letter to Sviatoslav. He promptly returned and defeated the Pechenegs, who continued to threaten Kiev. Sviatoslav refused to turn his Balkan conquests over to the Byzantines, and the parties fell out as