On one part of our property, there are three types of boundary markers: surveyor's tape, a barbed wire fence, and these tree blazes. They don't always precisely agree, but are usually within 10 or 20 feet of each other.
I don't know how old the painted markers are. The fence is rusty and has trees over it in a few places. I wonder if previous owners kept cows here... otherwise why bother to put up a fence in such hilly terrain? Nowdays it's not going to keep much of anything in or out, but it does a fairly good job of following the property line.
The ground in this area is extremely rocky, so the trees may be older than they appear.
I know it sounds corny, but - I wish the trees could talk! I'd love to hear their stories.