The Byzantine Empire under the Macedonian dynasty was engaged in a long and hard war with the First Bulgarian Empire. In the year 1000, the Byzantine generals Theodorokanos and Nikephoros Xiphias captured the former Bulgarian capitals of Pliska and Great Preslav, along with Little Preslav, extending Byzantine control over the northeastern portion of the Bulgarian state (Mysia and Scythia Minor). At the same time, Byzantium was instrumental in the Christianization of the Kievan Rus' and of other medieval Slavic states.