A common truism is to say that "history is written by the winners." When it comes to the story of hip-hop, most fans seem to only remember the Greats - the artists that have made an undeniable impact in the course of hip-hop history. Warm memories are associated with the Greats. Nobody forgets Rakim, Nas, OutKast, Run-D.M.C., Snoop Dogg, Jay Z or the Wu-Tang Clan. Their place is permanently etched in canon and they will not be soon forgotten. Their names will cause chills to run down the spines of hip-hop's most dedicated fans

Of course, the successes are only one part of hip-hop history. Thousands of acts have released hip-hop albums over the years which means there are plenty of groups that have slipped through the grasp of time. Not everybody who releases an album can be a huge, generational-defining star. Some lacked talent. Some lacked luck.

The forgotten stories of hip-hop need to be told as well to remind us that chance is fleeting and you need to make the most of a given opportunity even if you never truly succeed. With this in mind, XXL has compiled a list of 21 great hip-hop acts that have been largely forgotten through time. These acts might not have been the biggest stars but their legacy continues to exist through their music.

Today, we celebrate the forgotten.