A Federation colony overrun by Talarian forces during the border conflicts, where the infant Jeremiah Rossa lost his parents and was taken to be raised as a Talarian.
Galen IV was a Federation colony near Talarian space, referred to in the fourth-season Next Generation episode Suddenly Human.
During the Galen border conflicts, Talarian forces attacked the colony and killed its inhabitants. Among the dead were the parents of Jeremiah Rossa, grandson of Starfleet Admiral Connaught Rossa. The Talarian captain Endar, who had lost his own son to the fighting, found the small boy alive and, following his people's custom, claimed him and brought him up as his son under the name Jono.
In 2367 the Enterprise-D rescues a group of Talarian cadets from a damaged training ship and finds a human teenager among them. Records of the Galen IV massacre identify him. After trying to reawaken his human past, Picard accepts that Jono's home is with Endar.