During the long years of warfare under Tsar Simeon I the Great (893–927), the country was exhausted. The constant wars were unpopular enough so that 20,000 people sought refuge in Byzantium because of Simeon's "warlike rush and relentless intentions". His successor Peter I concluded a favourable peace treaty with the Byzantines, but the situation inside the country saw no improvement. There were many reasons for the decline — some historians dismiss Peter I as a weak ruler, incapable of handling his own family (two of his brothers rose up against him). Furthermore, in the mid-10th century the new Bogomil heresy spread itself widely over the country. The Bogomils preached that people must not follow secular authorities, pay taxes or enroll in the army. As a result, the Bulgarians were unable to stop the Magyars, who looted and plundered the countryside, further contributing to the grim situation of the state. When the Byzantines paid the Rus' "knyaz" Svyatoslav I to invade Bulgaria in 968, Peter I could send only 30,000 men against the 60,000 strong invading force. During the Rus' invasion between 968 and 971 the Bulgarians "de facto" lost control of the north-eastern parts of their country, including the capital Preslav, and in 970, Svyatoslav massacred 300 Bulgarian nobles, the elite of the Bulgarian nation and army, in Silistra.