Sunagakure

is one of the five great ninja villages, and as such has a Kage, known as the Kazekage, as its leader. The symbol on their headband is of an hourglass-like symbol, which is presumed to a gourd of some sorts. (This would make more since, concluding one of the main character's from Sunagakure wears one on his back.)

With its military forces being scaled down by the Land of Wind's Feudal Lord, the Fourth Kazekage realized that they had to increase the quality of each ninja to maintain a military force, Gaara being one of the results of that.

As more time passed, the lord started commissioning Konoha with requests he should have made to Sunagakure. On top of that, he began cutting back on Sunagakure's budget. The Fourth Kazekage realized that if he didn't act quickly, Sunagakure would be in danger of disappearing, so he joined forces with Otogakure in an attempt to destroy Konoha and force the lord to re-establish Sunagakure's military force if he wished for his country to continue existing. With the failure of the attack and the death of the Fourth Kazekage caused by the betrayal of Otogakure, Sunagakure re-allied with Konoha, and Gaara, Temari, and Kankuro assisted Konoha during the mission to retrieve Sasuke. Gaara eventually became the Fifth Kazekage.