In 1907, Prince Luitpold, regent of the Kingdom of Bavaria, selected the area near Grafenwöhr as the place best suited for training of the Bavarian Army.
Construction began in 1908 and by 1915, the training reservation covered an area of 37 square miles (96 km2). The first artillery round was fired in the training area at 0800 hours on June 30, 1910.
Throughout World War I, from 1914-1918, the area was used for training and equipping of combat units.
After the end of the war, the Berlin High Command utilized Grafenwöhr Training area for the 100,000 man German army.
In 1936, the training area was expanded to the present size of 90 square miles (230 km2). On 5 and 8 April 1945, the camp and town were subjected to Allied air raids. On 20 April 1945, the last German Commander of the training area surrendered to the American forces.
After World War II it became an important Cold War training site for the United States Army and allied forces
It has been and still a army training camp. I looked up various web sites concerning comcentration camps and military camps, Grafenwohr isn't listed anywhere as a concentration camp but is listed a military base.
http://www.grafenwoehr.com/%2851zko2urfsl05nvmk5ttrmrl%29/reference.aspx?f_k_=1520113&ref_ID=22702