Nothing is known of the time before the first era.

The Primary Races came upon Myaasia at aproximately the same time. The way they came is a mystery.
Kuor and Valris were present at this time.

The Primary Races start to consolidate and build empires.

First mention of dragons and other elemental beings, also first mention of Dural.

Two great empires come into being: The Iylari and the Uruk-Hai.
The empires eventually come into conflict.

The Great Elf-Orc-Wars, with other races as either allies or victims in a war to the death.
The wars lasted for about 200 years killing uncounted millions. The total population of Myaasia went down to about a quarter of the prewar levels.
Eventually both armies ran out of forces, as both Iylari and Uruk-Hai bred slowly and the subject races started to revolt, bringing down the two empires.
Thus up to this day, the Uruk-Hai and The Iylari are low in numbers.
First mentions of Reann.

After the great wars ended, the counting of periods started again with the beginning of the second era