Old American Indian necklace

My brother-in-law received this old Indian necklace from his Mother-in-Law who told him that it had been in her family for several generations. It appears to be made from hand made beads on an old cotton string. The 'cowbell' also appears to be hand made. Can anyone tell me if this is an authentic Indian artifact, any suggenstions on age or value, etc. Any opinions would be appreciated.