Finding Old Tribal property lines

I have been trying for quite a few years to prove/disprove the family tradition of my husband's Indian blood line. Supposedly, it comes down from his ggrandmother, Josephine Sain b. 1868 in Tennessee  - I'm guessing Warren County since that's where most of the family came from. I don't know if her father, Isham D. Sain b. 1843, Warren County, TN was of Indian blood or her mother of which I have no information on, including name. My husband's family grew up believing they were of Pottawatomie descent. From the shows I've been watching on History Channel, it appears they may have been Cherokee or Choctaw. My question: Where would one find "tribal property lines" (for lack of better term) dating back to 1821 in the Tennessee area? This is when his ggggrandfather, Samuel Sain, was born - if the Indian blood came from the paternal side. If it came from the maternal side, I have no clue who Isham married - haven't been able to find this. Samuel married Sarah Pope Powell, also born in Warren County, TN. Her father Samuel Powell was born in North Carolina & her mother, Nancy Clark was born in TN.  I have no clue as to what tribes were in NC in 1795. Any help on where I can find old maps, etc. would be greatly appreciated.