Breath of Fire

From the introduction:

In an age long past, this world had only one continent. All its many races lived in a state of technological bliss thanks to their advanced understanding of science and magic. But they had poisoned their own land in the process, turning large swaths of the northern portion into a desert. The people attempted to use their machines to hold back the ever growing desert, but quarreling and wars disrupted the effort. Soon, the Desert of Death covered much of the northern half of the world.