With older relics, the main question becomes for what purpose was the relic used?  Why is it important?  The Native American Graves Protection and Repatriation Act has thrust to the forefront the importance of a societies ability to best protect their culture.  When buying Native American Indian art that is older, ensure that you understand its significance and, if possible, identify the provenance.  Provenance is not a guarantee.  there are numerous museums that have provenance from pieces that were taken from a grave.

Predominantly, what we now consider art had more humble beginnings.  Most pieces started with an utilitarian or functional need or was an important part of trade.  Pottery is not a 'new' concept.  In fact, there are numerous examples of Anasazi pottery.  Navajo jewelry, greatly influenced by Mexican silversmiths, was an important store of wealth for trade.  A person could 'invest' hours and raw materials for a piece of jewelry and then 'spend' it later for food.  Baskets were created for storing of food, harvesting, and, to some extent, ceremonial.   

Below is a list of tribes and the art form that they are most known.  There are many tribes individuals from almost every tribe that create jewelry.  All of it is beautiful and well made.