Tatooine is a central world in Star Wars boasting an incredible amount of significance... And is often described by those that live and travel there as the complete opposite of that.
It is sand. Endless, barren, total sand. If something is alive out in the desert it is almost universally hostile to anything else. Some exceptions exist, scavengers who pick over the wreckage of what came before like Jawa's, but for the most part it is as dangerous a world as any other. To walk out into the deep desert is essentially suicide, and only a few creatures can live on Tatooine without a great deal of preparation beforehand. It has Two suns, and although many races live here, few actually are indigenous to Tatooine.
Most significantly Darth Vader was born here, which in and of itself makes the world important. But his son Luke was also raised here which combine into the fact that this world is more significant than many other planets put together because the origins and motivations of these people start here and dominate in the Star Wars Films.
In the very beginning, (as told by stories handed down in Sand people lore depicted in Knights of the Old Republic)Tatooine was a world lush with life. The inhabitants were space faring, prosperous, and did not (as their decedents claim) ‘Walk with the Land’.
Than the Builders came. The builders spread to all places thanks to the Infinite Star Forge fueling their empire, collecting Tatooine before utterly destroying it, capturing slaves, and moving on.
Those Tatooine that survived this holocaust did so by staying underground, and when they emerged centuries later they claimed victory over the sandy world. They had no idea that the reason the builders did not return was that the empire had collapsed and Tatooine was insignificant.
Over the centuries the survivors went into the wastes looking for any means to live on. Wrappings to conserve water, early weapons crafted out of not much more than sticks, and a tradition of oral histories to remember the past errors of a decadent society began. Only small numbers of these new ‘Sand people’ could be supported, so wandering nomadic tribes became the norm of what was once a much more civilized society.
Far far far later, aliens came to Tatooine again and begin cycles of building and abandoning structures on Tatooine. The local sand people were rightfully treated as hostile by all waves of these migrants. Sand People hated these new interlopers because they represented exactly what brought the wrath of the heavens in the first place. So they make every effort to remove them, with varying degrees of success.