The Tale of Years of the Third Age
The Tale of Years of the Third Age is the eighth chapter of The Peoples of Middle-earth, the twelfth book in the series The History of Middle-earth. This chapter describes the writing and development of the history of the Third Age that would be published in the second part of Appendix B.
 Earliest Timeline
The first version of the Tale of Years of the Third Age begins with the death of Isildur, declaring it Year 0. From there, Sauron is said to have reawoken and entered Mirkwood in 1000, where he established Dol Dugul (in the final version this will become Dol Guldur).
In 1100, Deagol and Smeagol came across the One Ring. Smeagol killed Deagol, became Gollum, and entered the Misty Mountains by 1105. Separately, the brothers' people multiplied, crossed the Misty Mountains in 1300, and became Hobbits. (At around this time Orcs began to reappear.) In 1500 the Hobbits settled at Bree. A century later, Marco and Cavallo crossed the Brandywine and the king at Northworthy granted them the Shire. (This event marks the beginning of Shire-reckoning.)
 About the Text
The earliest version of the Tale of Years of the Third Age was a short text that seemed closely related to the version of the Tale of Years of the Second Age which Christopher Tolkien had designated T2 in the sixth chapter, The Tale of Years of the Second Age. Because of this connection, although the two manuscripts were clearly distinct from each other, Christopher designated the relevant Third Age document T2 as well.
JRR Tolkien provided Shire-reckoning dates for all events that had them in this first timeline, but Christopher declined to include these.