I am by no means an expert & have a few pieces similar to yours that I have been trying to research also. Seed beads reached the plains Indians in the mid-1840s. From what I have found all the pieces of bead work I have looked at no matter how old I find they are EXPERTLY done, Very straight lines, Perfect matching patterns, very little to no stitching apparent on front of pieces. Possibly yours was reworked at a later date due to damage but the stitching on the bottom point before the tassels is very apparent on the top of your piece. I have found very little info on dating my pieces, tribe etc.... I believe an expert will need to be found for a hands on examination of my pieces.