The drum is used by shamans for many functions, depending on your geographic location and needs of the shaman. There are shamans who use it to make invocations, to retain and even spirits to heal the sick.
But perhaps, the drum was, is and will be a means to achieve altered states of consciousness and help your rhythm sound, to enter other worlds, connecting with your Nahual, the spirit world, in contact with Mother Earth and enter contact your inner power.
It is said that the drum is "the shaman's horse", ie a channel or a medium that gives the shaman of his power and helps you travel the world of spirits.
This sacred object of production as well as each and every tradition or culture, making this the subject of power, has a specific ritual.
An example of this is that access to the forest Samoyeds blindfolded and the shaman is able to find the sacred tree which provide wood for drum making.
Another example of this is that the sacred tree Altaianos found through dreams or visions that tell cahmán tree location that will give the wood for manufacturing.
The drum is present in almost every culture, in very many cults and rituals, from North America, through the Arab countries, Africa, Europe, Japan, Tibet ... the drum is considered a necessary object to an end.
Once an Indian told me personally:
"You the Spanish came and took the precious stones and gold. If you would have been also drums and dances, perhaps you would be happier and be in communion Mother Earth".
That reason was.