I hardly agree with James Green's recommendation to do DNA testing! I doubt there are any
Cherokee native Americans with sir names Killian but you can verify it with DNA. You have to have documented proof and DNA does that! The "Andreas Killian Descendants Historical Association of North Carolina also has a great website you can look at www.andreskillian.com.
Our Andreas branch Killians did not originate from Ireland or Saint Killian but Germanic per our German researcher William McCreight research. Following the same latitude (wagon/road) is a good assumption as Ed Killian suggested. Do the DNA test it can verify if your oral tradition from family members is correct or hearsay.