Sorry this is so vague, it has been a while since I worked on this family.
I had an ancestor, ARchibald Allen (aa) of Fauqueir county Va. He was born circa 1722 in Westmoreland or King George County Va. He had a son that was a rev. war vet and moved to Tennesee. I can't remember the name off hand, but; do remember that he had a son named Archibald. If you look in the complied pensions abstracts for the Allens, I think you will find your Allen.