In connection with Ghaymán a few words may be added respecting the castles in Yemen, of which the ruined skeletons rising from solitary heights seem still to frown defiance upon the passing traveller. Two thousand years ago, and probably long before, they were occupied by powerful barons, more or less independent, who in later times, when the Ḥimyarite Empire had begun to decline, always elected, and occasionally deposed, their royal master. Of these castles the geographer Hamdání has given a detailed account in the eighth book of his great work on the history and antiquities of Yemen entitled the _Iklíl_, or 'Crown.'[68] The oldest and most celebrated was Ghumdán, the citadel of Ṣan‘á. It is described as a huge edifice of twenty stories, each story ten cubits high. The four façades were built with stone of different colours, white, black, green, and red. On the top story was a chamber which had windows of marble framed with ebony and planewood. Its roof was a slab of pellucid marble, so that when the lord of Ghumdán lay on his couch he saw the birds fly overhead, and could distinguish a raven from a kite. At each corner stood a brazen lion, and when the wind blew it entered the hollow interior of the effigies and made a sound like the roaring of lions. [Sidenote: Zarqá’u ’l-Yamáma.] The adventure of As‘ad Kámil with the three witches must have recalled to every reader certain scenes in _Macbeth_. Curiously enough, in the history of his son Ḥassán an incident is related which offers a striking parallel to the march of Birnam Wood. Ṭasm and Jadís have already been mentioned. On the massacre of the former tribe by the latter, a single Ṭasmite named Ribáḥ b. Murra made his escape and took refuge with the Tubba‘ Ḥassán, whom he persuaded to lead an expedition against the murderers. Now Ribáḥ's sister had married a man of Jadís. Her name was Zarqá’u ’l-Yamáma--_i.e._, the Blue-eyed Woman of Yamáma--and she had such piercing sight that she was able to descry an army thirty miles away. Ḥassán therefore bade his horsemen hold in front of them leafy branches which they tore down from the trees. They advanced thus hidden, and towards evening, when they had come within a day's journey, Zarqá said to her people: "I see trees marching." No one believed her until it was too late. Next morning Ḥassán fell upon them and put the whole tribe to the sword. [Sidenote: Ḥassán murdered by his brother.] [Sidenote: Dhú Ru‘ayn.]