Ostmark (German: [ˈɔstmaʁk]) is the name given to a currency denominated in Mark which was issued by Germany in 1918 for use in a part of the eastern areas under German control at that time, the Ober Ost area. The currency consisted of paper money issued on 4 April 1918 by the Darlehnskasse in Kowno (Kaunas) and was equal to the German Papiermark. The Ostmark circulated alongside the Imperial rouble and the Ostrubel, with two Ostmark equal to one Ostrubel.