The Battle of Boulgarophygon was fought in the summer of 896 near the town of Bulgarophygon, modern Babaeski in Turkey, between the Byzantine Empire and the First Bulgarian Empire. The result was an annihilation of the Byzantine army which determined the Bulgarian victory in the trade war of 894–896.

The war ended with a peace treaty which formally lasted until around Leo VI's death in 912, and under which Byzantium was obliged to pay Bulgaria an annual tribute in exchange for the return of allegedly 120,000 captured Byzantine soldiers and civilians. Under the treaty, the Byzantines also ceded an area between the Black Sea and Strandzha to the Bulgarian Empire, while the Bulgarians also promised not to invade Byzantine territory.

Simeon often violated the peace treaty with Byzantium, attacking and conquering Byzantine territory on several occasions, such as in 904, when the Bulgarian raids were used by Arabs led by the Byzantine renegade Leo of Tripoli to undertake a maritime campaign and seize Thessaloniki. After the Arabs plundered the city, it was an easy target for Bulgaria and the nearby Slavic tribes. In order to dissuade Simeon from capturing the city and populating it with Slavs, Leo VI was forced to make further territorial concessions to the Bulgarians in the modern region of Macedonia. With the treaty of 904, all Slavic-inhabited lands in modern southern Macedonia and southern Albania were ceded to the Bulgarian Empire, with the border line running some 20 kilometres north of Thessaloniki.