The city's fortune underwent a dramatic downturn at the end of the 960s, when it was occupied by Kievan Prince Sviatoslav. The ensuing war between Rus' and Byzantines left the city burnt and ravaged by the army of Byzantine Emperor John I Tzimisces. The conquerors took away the treasury, the Bulgarian Tsar's regalia and a large part of the library of Simeon. Although the city did not lose its importance in the next three hundred years, the neighbouring outskirts and the big monasteries became desolate, the economy lost its vitality and significance.