Help understanding claiming land, how to "capture"?

Currently in my game, players can use a tool to place pillars, once 2 pillars are placed it creates a wall. The idea is to claim land by walling off portions of the land.

I'm trying to figure out a way that once a completed area is walled in it would "Claim" that land for the player that built the walls. "Claim" going as far as just getting a numerical value for the amount of land you walled in.

Any articles/docs or just thoughts on this would be helpful.

Thanks for any help!

EDIT: Wondering if a grid system like this would be too laggy because of creating so many parts

local base = game.Workspace.Baseplate
base.Transparency = 1

local model = Instance.new("Model", game.Workspace)
model.Name = "Grid"

for i = 1, 50, 1 do 
    for j =1, 50, 1 do
        local part = Instance.new("Part", model)
        part.Name = i..", "..j
        part.Anchored = true
        part.Size = Vector3.new(8,0.25,8)
        part.Position = Vector3.new(i*8, 0.125, j*8)
    end
end