Danube-Auen National Park on both land and water, and other invertebrates, the total number of species in Donau-Auen National Park is estimated to be at least 5,000. Danube-Auen National Park Donau-Auen National Park () covers 93 square kilometres in Vienna and Lower Austria and is one of the largest remaining floodplains of the Danube in Middle Europe. The German word Aue (variant Au) means "river island, wetland, floodplain, riparian woodland", i.e. a cultivated landscape in a riparian zone. The words Aue and Au occur in a large number of German place names—including Donau, the German word for the Danube River—and refer to forests,
Bulgarian lands across the Danube 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 1371-1422. 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