I had a similar problem in an Oasis scenario (Duqqura?). I had military however and every now and then went hunting...
I agree with VirtuviusAIA - use police. In one problem area I put a house and a police station, and enclosed the stretch with roadblocks to keep the constables on the beat. This was fine, but I had the occasional fire ...
I also found that after a while the hyena packs moved on to another hunting ground. Maybe my people got too stringy for them?
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