Bulgarian lands across the Danube

In the Middle Ages the Bulgarian Empire controlled vast areas to the north of the river Danube (with interruptions) from its establishment in 681 to its fragmentation in 1371. These lands were called by contemporary Byzantine historians Bulgaria across the Danube. Original information for the centuries-old Bulgarian rule there is scarce as the archives of the Bulgarian rulers were destroyed and little is mentioned for this area in Byzantine or Hungarian manuscripts.

After the disintegration of Great Bulgaria following Khan Kubrat's death in 668 a large group of Bulgars followed the third son of the great Khan, Asparukh, who headed westwards. In the 670's they settled in the area known as the Ongal to the north of the Danube delta. From there Asparukh's cavalry in alliance with local Slavs annually attacked the Byzantine territories in the south. In 680 the Byzantine Emperor Constantine IV lead a large army to face the Bulgars but was defeated in the battle of Ongal and as a result the Byzantines were forced to acknowledge the formation of a new country, the First Bulgarian Empire. The northern border of the country followed the southern slopes of the Carpathian mountains from the Iron Gates and reached the Dneper river (or possibly just the Dniester river) to the east.

The Bulgarian's main rivals in the area were the Avars to the west and the Khazars to the east. The latter were a serious threat: after they crushed the resistance of Kubrat's eldest son, Bayan they marched westwards. They waged a war against Asparukh who perished in battle fighting the invaders in 700.

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