The four stamps in this series show the ceremonial masks of tribes from the Pacific Northwest. The Pacific coast of northwestern North America was hospitable for the Native American inhabitants because of the many salmon-spawning streams located in that region. Tribes inhabiting this region placed great emphasis on individual and group wealth, which was measured by the enumeration of possessions including cedar -bark blankets, shells, dried fish and fish oil, dugout canoes, coppers, and slaves. Wealth was exchanged on a number of occasions through reciprocal potlatch or gift-giving sessions that took place between parents and children, among relatives, and even between competitors and enemies. Religious practices, based mainly on a faith in mythical ancestors, often took on a dramatic flair with public presentations involving encounters with the spirits.