On this page of the guide to Back 4 Blood you will learn more about the Horde, which can cause you a lot of trouble. You will learn how to deal with it, and how to avoid causing one at all, which is very important for saving resources.
Maps in Back 4 Blood are besieged by all kinds of zombies. Completing a given level without summoning a horde can sometimes be difficult. If a horde is summoned, though, completing the level will become even harder.
A horde is simply a large group of zombies that will instantly attack you as soon as one of the players lures it. It forces you to fight a large number of opponents, which may result in losing a lot of health and resources. If any of you have already summoned the horde, it's best to find a good position to defend against it from a safe spot. These can be cramped buildings, car roofs, or higher locations.
You can easily lure the horde to yourself, so you have to watch your own actions carefully. Watch out for crows specifically, because they will alert the horde if you spook them. It's best to remain quiet and not approach them. Additionally, ping the crow location with a marker, to let your companions know about it.
Also, blowing up cars can also cause a horde to appear near you, so try not to blow up too many cars.