[Openurmind]

There are Bristlecone pines 5,000 years old. :)

[Vigilanteman]

. . . making aforementioned junipers young whippersnappers by comparison.

My point, of course, being that going back 1200 years wasn't a problem to check tree rings.

I believe scientists use a hollow bore of less than 1/4" diameter and inject the tree with its own resent to heal the bore when finished.