The tribe that measured their actions in terms of its impact on the future up to the seventh generation was (is) the Iroquois. My husband wrote a book on ecology recently in which the Iroquois model was featured. Unfortunately for us, the Iroquois had less impact with their civilization than we have with ours, due to technological advances and unbridled greed.

The Iroquois government manifesto also inspired the US constitution, by the way -- it's nearly a direct copy.