The tribe you are thinking of is the Lombards. The name is derived from Langobardi, which literally means long beards.
Wearing the hair in the form of a beard wasn't something the Lombard women did routinely. The Lombard sources (Paul the Deacon and the Origo Gentis Langobarorum) report the story as a foundation myth.
Here's the Wikipedia translation from the Origo:
The text mentions an island
Scandanan, the home of the Winnili. Their ruler was a woman called Gambara, with her sons Ybor and Agio. The leaders of the
Vandals, Ambri and Assi, asked them to pay them tribute, but they refused, saying they would fight them. Ambri and Assi then went to Godan, and asked him for victory over the Winnili. Godan replied that he would give the victory to whomever he saw first at sunrise. At the same time, Gambara and her sons asked
Frea, Godan's wife, for victory. Frea advised that the women of the Winnili should tie their hair in front of their faces like beards and join their men for battle. At sunrise, Frea turned her husband's bed so that at he was facing east, and woke him. Godan saw the women of the Winnili, their hair tied in front of their faces, and asked "Who are these longbeards?", and Frea replied, since you named them, give them victory, and he did. From this day, the Winnili were called
Langobardi, "longbeards".
Comment: I can't see why the women needed to wear their hair like beards -- just being in the right place at sunrise would have worked. However, the author isn't around to answer the question, so we are stuck with the story as is.