There is almost no truth to his comments (I say "almost" for a reason which I will explain).
What your neighbor is alluding to is that he may have received ownership
of your property through adverse possession
. This is the Oregon statute:
SECTION 1. ORS 105.620 is amended to read:
105.620. (1) A person may acquire fee simple title
to real property by adverse possession only if:
(a) The person and the predecessors in interest of the person have maintained actual, open, notorious, exclusive, hostile and continuous possession of the property for a period of 10 years;
(b) At the time the person claiming by adverse possession or the person's predecessors in interest, first entered into possession of the property, the person entering into possession had the honest belief that the person was the actual owner of the property and that belief:
(A) By the person and the person's predecessor in interest, continued throughout the vesting period;
(B) Had an objective basis; and
(C) Was reasonable under the particular circumstances; and
(c) The person proves each of the elements set out in this section by clear and convincing evidence.
(2)(a) A person maintains "hostile possession" of property if the possession is under claim of right or with color of title. "Color of title" means the adverse possessor claims under a written conveyance of the property or by operation of law from one claiming under a written conveyance.
However, under this standard your neighbor must prove "good faith"--meaning that he really did think that the land belonged to him, which is typically hard to do. If, however, the possession lasted for more then 10 years, he may actually have a case against you.
Dimitry Alexander Kaplun, Esq.