The massive Dragon's Spine was one of the oldest asteroid fields in the vicinity of the Tatoo star system. Located right outside Tatooine, a major planet in the system, it snaked across the vast expanse of space around the planet and was generally safe enough to serve as a center point of navigation for many explorers.
The Dragon's Spine asteroids in the waning days of the Galactic Republic
At some point before the Boonta Eve Classic of 32 BBY, an unidentified spacer from another galaxy collided with an asteroid while flying through the field, which caused their starship to enter a spin and crash on Tatooine, in the vicinity of Mos Espa.
Much to the consternation of the local crime lord Jabba the Hutt, his Whiphid competitor Lady Valarian maintained a military presence in the Dragon's Spine during the height of the Galactic Civil War. At the time, even the Galactic Empire had ordered their fleets to stay away from the Spine and the conflict that raged within the asteroid field.
There are only a minority of sources that show an asteroid field right outside Tatooine, as none can been seen in the six Star Wars movies. The first of these sources was the 1993 video game Star Wars: Rebel Assault. The field also appeared in Star Wars Math: Jabba's Game Galaxy, a educational video game released in 1999, and in the now defunct Star Wars Galaxies, in which it was first identified as the Dragon's Spine.