To understand drum protocol, a drum may be thought of as a person or being and is to be regarded and respected as such. Drum etiquette is highly important. There are regional variations. The drum is the central symbol of Oklahoma pow wows and is located in the center of the dance floor and pow wow (which are themselves shaped in concentric circles). Southern drums are suspended by four posts, one for each direction. Northern drums are set up on the outside of the dance area, with the host drum in the best position. Drummer-singers are expected to remain at their drum and ready to sing at any moment's notice; a dancer might approach the drum and whistle, fan or gesture his staff over a drum to indicate his request for a song even if it is not that drum group's turn to sing. In some regions it is considered disrespectful to leave a drum completely unattended. Some drum groups do not allow females to sit down at their drum but welcome them to stand behind the drummers and sing backup harmonies; the reasons for this point vaguely to a variety of tribal stories that attempt to tell the history of drumming as each group understands it. The drum is offered gifts of tobacco during giveaways and musicians acknowledge this by standing.