The
Byzantine–Bulgarian wars were a series of conflicts fought between the
Byzantines and
Bulgarians which began when the
Bulgars first settled in the
Balkan peninsula in the 5th century, and intensified with the expansion of the
Bulgarian Empire to the southwest after 680 AD. The Byzantines and Bulgarians continued to clash over the next century with variable success, until the Bulgarians, led by
Krum, inflicted a series of crushing defeats on the Byzantines. After Krum died in 814, his son
Omurtag negotiated a thirty-year peace treaty. In 893, during the next major war,
Simeon I, the Bulgarian emperor, defeated the Byzantines while attempting to form a large Eastern European Empire, but his efforts failed.