I recently finished a book called The Sex Lives of Cannibals: Adrift in the Equatorial Pacific by J. Maarten Troost. Contrary to the title, there is very little about cannibals, and less about sex. It is, however, a fascinating book about living in the equatorial island nation of Kiribati. The book is also the only reference I have found to a communist society that actually lives and sustains itself.

According to Wikipedia:

Pure communism in the Marxian sense refers to a classless, stateless and oppression-free society where decisions on what to produce and what policies to pursue are made democratically, allowing every member of society to participate in the decision-making process in both the political and economic spheres of life.

The major reason this system has never been reached in a large scale is that people seem to naturally oppress others so that they can have more things and more power.