These people were renown for their skill with horses, and Hannibal, that clever dude, got the idea to use them as a tactical device in his ongoing wars. And he was wildly successful.
Western cavalry at this time was for all practical purposes simply an infantryman on a horse.
The Numidians rode bareback, no stirrups, no bridle, just a rope around the horse’s neck. They had short spears, and as a group, fought on the fringes as a fluid body whose biggest asset was the ability to pursue a fleeing army and pick them off one by one. They were almost invincible.
There is, of course, a great deal more to all of this, and all of it quite fascinating. I love this stuff, especially in small doses such as this.