Southern Fire by Juliet McKenna

Southern Fire by Juliet McKenna
Published by: Tor; July 1, 2005
ISBN: 0765314118
Genre: Fantasy

Here's the blurb:

The Aldabreshin warlord, Daish Kheda, sees calamity sweeping the islands between his own domain and the supposedly empty ocean to fall on the southernmost islands of the Archipelago. Son of Daish Reik, reader of portents, giver of laws, healer and protector of all his domain encompasses, he must act quickly and decisively. While other warlords cannot look beyond their own selfish concerns to see the true danger about to overwhelm them, or are overwhelmed by fear, Kheda's people look to him. But what can he do, if the only defence against the dark magic that threatens to overrun every island of the Aldabreshi is wizardry? To wield that anywhere in the Archipelago means certain death.

Determined not to repeat myself as a writer, I turned from stories where wizards were respected and mostly trusted to explore the Aldabreshin belief that magic is a corruption of nature. I soon found their implacable loathing of wizards inextricably linked with their reliance on portents and omens which led naturally to a deeper understanding of the cyclical nature of their world view. But what can they do, when magic turns up causing mayhem, and wild, savage magic, not the civilized wizardry of Hadrumal. Aldabreshin warlords are absolute rulers in every sense but how can they fight unfettered sorcery?

You can read the opening chapter here.
Here's a review from crowsnest
Here's a review from sunburst
Here are some interviews