James Espy (1759-1834) was born in Cumberland County PA, removed to Mecklenburg Co NC with his father and settled in Wilkes(now Oglethorpe) County GA. His father Thomas Espy (1729-abt. 1794) was born in Northern Ireland, married in Cumberland County PA, removed to Mecklenburg NC in 1770 with his brother Robert Espy and left for GA in 1786 settling in Wilkes(Oglethorpe) Co GA.
James fought at Kings Mountain with his twin brother John(1759-1846)and brother Samuel (1758-1838). Samuel is mentioned in Drapers "Kings Mountain and Its Heroes". James also fought at Guilford Courthouse. Their father Thomas was a member of the Tyron County Committee of Safety during the Revolutionary War.
James brother Joseph Espy(1771-1848) and wife Mary Barnett are buried in the old Jackson Street Cemetery located on the Univ Of Georgia Campus across from the library. James is mentioned in Wilkes County GA by 1791. Oglethorpe Co was created in 1793 from Wilkes Co. James was an elder in Beth-Salem Presbyterian Church originally located near Crawford Oglethorpe Co GA and later reorganized and moved to Lexington, Oglethorpe Co GA. A Georgia historical marker at the site lists James and his wife Mary as charter members.
James and wife Sarah Baker(abt.1761-1831) had a daughter Mary "Polly" Espy (abt.1799-1829) who married James Fullton(1788-1853).Mary died shortly after the birth of her last child in 1829. James Fullton died in Dade County GA and one child died in Chattanooga TN in 1858, so at least part of this family moved into the Northwest corner of GA.
I don't know about the Barber or White you mentioned, but it is likely that they moved into GA also. In "Annals of Athens" (Georgia), it mentions that the settlers of Sandy Creek were Presbyterians from Virginia and North Carolina. Many of the original settlers of original Wilkes County GA were Scotch-Irish Presbyterians, many with Pennsylvania origins. Two groups moved from Cumberland County PA around 1786. It is probable that Thomas Espy joined up with one of these groups as they passed through NC on their way to GA following the Rev War. That may be another direction to look for Barber and White.