Tillman County is a county located in the southwestern part of Oklahoma, United States. As of the 2020 census, the population was 6,968. The county seat is Frederick. The Medicine Lodge Treaty of 1867 established a reservation in the southwestern part of Indian Territory for the Kiowa, Apache and Comanche tribes. The Jerome Commission started enrol…Tillman County is a county located in the southwestern part of Oklahoma, United States. As of the 2020 census, the population was 6,968. The county seat is Frederick. The Medicine Lodge Treaty of 1867 established a reservation in the southwestern part of Indian Territory for the Kiowa, Apache and Comanche tribes. The Jerome Commission started enrolling members of these tribes in 1892, a prerequisite to opening "excess" land for settlement by non-Indians. The first lottery was held on August 6, 1901. It was followed in 1906 by the "Big Pasture" Lottery.