Oberlin is a city in Decatur County, Kansas, United States. The population was 1,994 at the 2000 census. It is the county seat of Decatur County. On September 30, 1878, Northern Cheyenne fleeing from Indian Territory to their homes in the north, the Northern Cheyenne Exodus, attacked homesteaders near Oberlin, then a tiny hamlet. The Last Indian Raid in Kansas room in the Decatur County Museum and a monument in the town cemetery near the graves of the victims commemorate those depredations.