Tishomingo is the largest city and the county seat of Johnston County, Oklahoma, United States. The population was 3,034 at the 2010 census, a decline of 4.1 percent from 3,162 at the 2000 census. It was the first capital of the Chickasaw Nation, from 1856 until Oklahoma statehood in 1907. The city is home to Murray State College, a community college with an annual enrollment of 1,600 students. Tishomingo is part of the Texoma Region.