The Second Age of Mankind
In the Second Age of Mankind, mankind was sentient, and on the verge of space-faring.
The First Ones gradually left the galaxy to join Lorien's people beyond the Rim.
Lorien himself stayed behind at Z'Ha'Dum
The Shadows and the Volons remained to guide the younger races in their evolution. As a balance the Vorlons would promote order, and the Shadows would promote conflict and disorder, since the First Ones saw the wisdom in both.
The Vorlons would appear as angelic figures promoting local religions of the younger races, manipulating them to follow light, and doctrine. The Shadows would arrive periodically and incite war, fear, and chaos, which would make one race stronger, while destroying another.
This, was played out in a series of wars, called the Shadow Wars, in which the Vorlons would rally the troops together, when the Shadows would return to Z'Ha'Dum to mount their assault.
In this age, the Vorlons discovered Thirdspace, and attempted to hide their new Jumpgate in hypserspace.
The Great Machine was built on Epsilon 3.
The Minbari took to the stars, and other empires fell into flames.
In the Shadow War of 1250, the Minbari Federation emerged as the strongest race, they were more technologically advanced then all of the other races. The Narn were almost wiped out, when the Shadows used the Narn Homeworld as a base of operations, this made the Narn easy to conquer, when the Centauri Republic found them. Earth was not affected much in this war.
However, Valen, the Minbari Holy Figure who lead to the vanquishing of the Shadows planted the seeds of what would be called the Dawn of the Third Age of Mankind. Through prophecies, passed down through the Vorlons, the Rangers and Minbari Culture, Entil'zha Valen would predict specific events that the Vorlon Empire and the Minbari Federation would participate in. Events that would not take place for another 1000 years, including the Earth-Minbari War, Jeffrey Sinclair, the Babylon Project, Babylon 4, Babylon 5, the breaking of the Grey Council and the Final Shadow War. All of which would happen in the middle of the 23rd century.
The Dawn of the Third Age of Mankind began when the humans, the youngest of the space faring races met the Minbari, and the Earth-Minbari War began. The events resulting from this conflict would then elevate the younger races to challenge the manipulation of the Vorlons and the Shadows, and would promote Lorien, at the climax battle at Coriana 6, to take the Vorlons and the Shadows beyond the rim.
And in January 2261, the Third Age of Mankind had begun.