The idea is to dry the meat without cooking it(denaturing the protiens). Denaturing of protiens can happen at as low as 150 degrees F. It does happen very slow at this temp and the meat actually dries faster than the protiens denature. The closer you get to 200f the faster the protiens denature and you wind up with dry cooked steak, which is as bad as shoe leather. Salt included in the brine helps with this, as the drying process progresses the salt helps pull the moisture from the center of the meat. It can be done as low as 80f with good airflow. I have a propane fired oven and just with the pilot light on it stays about 100f in there. I have made jerky by just laying the strips on the racks and letting them stay there. This way can take 24-48 hours per batch. I did leave the broiler door cracked to allow better airflow. Of course this violates most health department standards of keeping raw meat in the danger zone(40f-140f) for more than 2 hours. So, do this at your own risk, however this is an ancient method of preserving meat for storage, and was common for both red meat and fish.