They are people in Africa who herd sheep and other animals. The
term could also refer to people who are wandering who play the card
game called Animal Herders.
Animal Herders is a card game for kids that is similar to Pokemon
but much more simple. The cards focus on a picture of either a clay
animal or a clay food. Two players build a herd and then battle one
herd against another. The more powerful herd wins while skill is
used in building the herd strategically and maintaining the herd
through the use of food.