The earlier settlements, known solely through material remnants but whose people's name for themselves remains unknown, led up to the invasion of Germanic tribes belonging to the Ingvaeonic group. Those were Chauci mentioned by Tacitus, and Frisians. The region between the rivers Ems and Weser was thereupon inhabited by the Chauci; however, after the second century AD there is no mention of the Chauci. They were partly displaced by Frisian expansion after about 500, and were later partially absorbed into the Frisian society.