"African masks are arriving from animistic cultures, tribes that do not believe in a single god, but instead attempt to stay in harmony with all the ancestors' spirits and nature's powers.

For the ritualistic ceremonies they split masks and figurines which are "permitted" by the village sorcerer. It's just following this empowerment which the masks could call upon the spirits and nature's powers."

Just how many different sorts of masks exist?

You've death masks for funerals, masks used throughout the harvest, searching masks, initiation masks. Moreover, There are several tribal art sellers in New York from where you can get many types of african masks.

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Many tribes also have disorder masks to stop and cure. The Pende tribe from Congo has fabulous items that reveal a split tormented character. Animal figures normally symbolise the forces of nature. The importance of particular masks, however, is still not known."

How old are those masks?

"For an African American it is not the era that's vital. Every generation makes masks. However, some distinctive samples are retained for generations. 

For an antique dealer and a collector a mask has to be at least fifty years old, rather with a traceable pedigree – a registered lineup of possession confirming the age of this merchandise. 

Normally, this implies it has been listed who brought it back in the colonies, or much better, it had been subjected to a Museum's temporary or permanent groups.