For a given Lipschitz domain Ω, it is a classical result that the trace space of W 1,p (Ω) is W 1−1/p,p (∂Ω), namely any W 1,p (Ω) function has a well-defined W 1−1/p,p (∂Ω) trace on its codimension-1 boundary ∂Ω and any W 1−1/p,p (∂Ω) function on ∂Ω can be extended to a W 1,p (Ω) function. Recently,[26] characterizes the trace space for nonlocal Dirichlet problems involving integrodifferential operators with infinite interaction ranges, where the boundary datum is provided on the whole complement of the given domain R d \Ω. In this work, we study function spaces for nonlocal Dirichlet problems with a finite range of nonlocal interactions, which naturally serves a bridging role between the classical local PDE problem and the nonlocal problem with infinite interaction ranges. For these nonlocal Dirichlet problems, the boundary conditions are normally imposed on a region with finite thickness volume which lies outside of the domain. We introduce a function space on the volumetric boundary region that serves as a trace space for these nonlocal problems and study the related extension results. Moreover, we discuss the consistency of the new nonlocal trace space with the classical W 1−1/p,p (∂Ω) space as the size of nonlocal interaction tends to zero. In making this connection, we conduct an investigation on the relations between nonlocal interactions on a larger domain and the induced interactions on its subdomain. The various forms of trace, embedding and extension theorems may then be viewed as consequences in different scaling limits.