13,000,000,000 BBY

13,000,000,000 Before the Battle of Yavin, also 12,999,996,347 Before the Treaty of Coruscant or 12,999,999,965 Before the Great ReSynchronization, was the approximate year, firmly in the Pre-Republic era, in which it was believed the galaxy was formed from universal debris. Over the ensuing eons, star systems and planets formed within the galaxy, with life and sentience growing upon these worlds' surfaces, leading to the events of galactic history.

The galaxy in 13,000,000,000 BBY
By the year 13,000,000,000 BBY, long before the Galactic Republic was founded, the Big Bang had already taken place, creating the universe. Many believed that it was approximately the year in which a cloud of dust and gas within the universe that was one-hundred-thousand light years across experienced a gravitic collapse, forming a disc of the same dimension. This disc was populated with approximately four-hundred-billion stars, becoming the galaxy.

Impact
The galaxy's stars developed orbiting planets over the succeeding eons. Half of these star systems maintained conditions favorable to life, ten percent of this half actually developed life, and only one in a thousand of the life-bearing worlds went on to bear true sentience. Life would still be emerging on planets in the galaxy by 5,000,000,000 BBY. Many of these forms of sentience would try to explain their conditions, forming religions. A number developed creation myths, detailing how their existence came to be,  whether that meant the creation of the galaxy, the formation of their world, or the origin of life. The Mandalorian religion had a creation tale called the Akaanati'kar'oya, "The War of Life and Death" in Basic, and posited that the stars in the sky were ancient Mandalorian leaders that had died. Life that grew on worlds separated by great distances, primarily twenty million sentient species, would go on to interact and integrate, experiencing and eventually recording galactic history.

Behind the scenes
Initially, 5,000,000,000 BBY was the approximate date of the creation of the galaxy, as established by a timeline in The Essential Guide to Alien Species (2001) by Ann Margaret Lewis. The Essential Atlas (2009) by Jason Fry and Daniel Wallace denoted the year 13,000,000,000 BBY as a modern date. This timeline alteration rectified a potential inconsistency. Before Lewis's Essential Guide was released, Goroth: Slave of the Empire (1995) by Nigel D. Findley placed 5,000,000,000 BBY as the year around which life first emerged on Goroth Prime&mdash;a planet which would have taken quite a long time to form, let alone develop life.