In the tales, the Otherworld is often reached by entering ancient burial mounds, such as those at Brú na Bóinne and Cnoc Meadha. These were known as sídhe (Otherworld dwellings) and were the dwellings of the gods, later called the aos sí or daoine sí (Otherworld folk). Irish mythology says that the gods retreated into the sídhe when the Gaels (Milesians) took Ireland from them. In some tales, the Otherworld is reached by going under the waters of pools, lakes, or the sea, or else by crossing the western sea. In Irish Immrama (voyage) tales, a beautiful young Otherworld woman often approaches the hero and sings to him of this happy land. Sometimes she offers him an apple, or the promise of her love in exchange for his help in battle. He follows her, and they journey over the sea together and are seen no more. Their journey may be in a boat of glass, in a chariot, or on horseback (usually upon a white horse, as in the case of the goddess Niamh of the Golden Hair). Sometimes the hero returns after what he believes is a short time, only to find that all his companions are dead and he has actually been away for hundreds of years. Sometimes the hero sets out on a quest, and a magic mist descends upon him. He may find himself before an unusual palace and enter to find a warrior or a beautiful woman who makes him welcome. The woman may be the goddess Fand, the warrior may be Manannán mac Lir or Lugh, and after strange adventures the hero may return successfully. However, even when the mortal manages to return to his own time and place, he is forever changed by his contact with the Otherworld.