From the Wikipedia page 
Deggendorf is a Landkreis (district) in Bavaria, Germany. It is bordered by (from the north and clockwise) the districts of Regen, Freyung-Grafenau, Passau, Rottal-Inn, Dingolfing-Landau and Straubing-Bogen.
The district was established in 1936. Minor changes of the borders occurred in 1972 and led to the present form of the district.