In episode 15 of season six, "East," Morgan and Rick team up to search for a missing Carol, and end up running into a man clad in intense body armor looking for his horse at a farm. Rick, lovable psychopath that he is, tries to shoot at the guy, but Morgan shoves his arm and saves the mystery man's life before saying, "Maybe he's from the Hilltop, maybe he's from somewhere else." We see him again in the finale, when he appears with a friend out of nowhere in the scene where Morgan narrowly saves Carol from being shot to death by a rogue Savior. We can't know for sure, but it definitely seems like the unknown character is from a community called the Kingdom.
In the comics, the Kingdom (similar to Alexandria and the Hilltop) is a group led by a man named "King" Ezekiel, a former zookeeper who runs his community — full of people wearing body armor, we might add — with the help of his pet tiger named Shiva (just go with it) in an abandoned high school. Ezekiel hates Negan and all that the Saviors stand for, so we can probably expect to see Rick use Ezekiel's hatred to his advantage next season. Lincoln somewhat backed this theory up, saying he doesn't know "when or where or how or who" the Kingdom will come to be, but that "it does seem like the world is growing."
