What is an Unengaged Unreached People Group (UUPG)?

After the initial meetings of Table 71 where the people group list was distributed among the partners and brought to the field, it was discovered that much work was needed in updating the list. Research collaboration led to the formation of a new website to house the data (http://www.peoplegroups.org). The current definition of a people group found on that website is: a people group is the largest group through which the gospel can flow without encountering significant barriers of understanding and acceptance. A more technical definition is available as a link from that site.
As the data was being assembled it became clear that there was a group of people groups with populations in excess of 100,000 each representing over 500 million people who were not only unreached, but as far as could be ascertained, no one was even trying to reach them. We call this set of people groups unengaged unreached people groups (UUPGs).