Lebanon is census-designated place and unincorporated community in Marshall County, Oklahoma, United States. It has a post office with the ZIP code 73440. Lebanon was settled in the late 19th century as part of the Chickasaw Indian Nation and was part of Pickens County. A Chickasaw Tribal Courthouse was located in Lebanon. About a mile to the east o…Lebanon is census-designated place and unincorporated community in Marshall County, Oklahoma, United States. It has a post office with the ZIP code 73440. Lebanon was settled in the late 19th century as part of the Chickasaw Indian Nation and was part of Pickens County. A Chickasaw Tribal Courthouse was located in Lebanon. About a mile to the east of Hauani Creek is the remains of the Burney School, a tribal school operated by the Chickasaws.