When it comes to years, the most accurate unbroken timelines are based on tree rings (and similar, such as annual layers of sediments). The longest, the Hohenhe

When it comes to years, the most accurate unbroken timelines are based on tree rings (and similar, such as annual layers of sediments). The longest, the Hohenheim Tree Ring Timeline (Central European pine) goes back to 10,461 BC, and researchers hope to extend it another 2,000 years back.