> By matching up the relative widths of rings from one tree to another, including from bogs and historic buildings, the tree record has now been pushed back to 13,910 years ago."

This is exactly how they did it.

edit: Imagine I have one 50 year old tree in the yard, and a house with a log in it that was cut 40 years ago from another 50 year old tree. They were both alive at the same time for 10 years. The relative thicknesses of the rings will match for the first 10 years of the tree and the yard and for the last 10 years of the log in the house, giving me a 90 year record.