Llyn y Fan Fach is associated in Welsh folklore with the Gwragedd Annwn, female fairies believed to live under the surface of lakes and rivers, who sometimes become the wives of humans. One such tale recounts how in the twelfth century there lived a widow at Blaensawdde near Llanddeusant in Carmarthenshire. One day she sent her son to graze their cattle on Mynydd Du near Llyn y Fan Fach, and there he saw a beautiful maiden sitting on the surface of the lake combing her hair. He tried to court her by offering her some bread and cheese, but she gently refused saying the bread was too hard, and she disappeared beneath the water. When he returned home and told his mother what happened, she advised him to try again next time using some unbaked dough. The maiden again kindly refused, saying this time the bread was too soft. The young farmer's mother then suggested using some bread that was lightly baked, and this time after offering it to her the maiden consented to marry him. However, she stipulated the condition that they should only be together until he struck her three times, upon which she would leave him forever. Being of mild temperament, to this he readily agreed. The maiden's fairy father gave her a dowry of as many sheep, cattle, goats and horses as she could count of each without drawing breath, and reminded the young man that if he ever struck her three times then she would leave him forever and the dowry would be forfeit. When they were married, they went to live at a farm called Esgair Llaethdy near the village of Myddfai. They were happy and prosperous and became the parents of three beautiful sons, but the wife continued to exhibit strange fairy behaviour such as weeping at weddings (because marriage often brings trouble) and laughing at funerals (because death brings release from trouble). At each instance of this her husband struck her a blow, not an angry or harmful one, but enough to break the terms of their marriage contract. Upon the third one she left him forever and took all their livestock back with her into the lake and to the fairy realm. However, she did not completely abandon her sons. From time to time she would reunite with them on the shores of the lake and teach them the arts of healing so that they and their descendants would eventually become the greatest physicians in the entire country. The sons were in time rewarded with land, rank and privilege, and became known as the Physicians of Myddfai.