The correct answers are the Ouachita Mountains and Red River Plains
The two of these are regions in Oklahoma are the Ouachita Mountains and Red River Plains.
Oklahoma was first known as the Indian territory before being accepted as a state on September 17, 1907. US President Theodore Roosevelt accepted and Oklahoma became the 46th state of the country.
The state of Oklahoma has seven regions that include South Eastern Oklahoma (Ouachita Mountains), the Green Country, Oklahoma Panhandle, Southern Oklahoma(Red River Plains), Northwest Oklahoma, South Central Oklahoma, and Southwest Oklahoma. In the prairie region of Oklahoma is easy to see Buffalos' herds.