If you search for references to potlach you will find gobs of positive portrayals of it as a gift giving festival with great symbolism as the giving or destroying valuables shows how wealthy you are. Both the Canadian and American governments banned potlaches for many years because of those mean old missionaries. I had a vague memory of the potlach that was so dark that the laws made sense. With a little digging, I found it here.The destruction of goods as a show of wealth could include either the freeing or killing of slaves, who were usually acquired specifically for potlach.
Source: Those Nasty White People