This royal city of Persia was built, as we have seen, on both banks of the Tigris, at a sharp and double bend of the river, fifteen miles below the modern Baghdad. Seleucia, on the right bank, was the original seat of the Alexandrian conquerors. On the opposite shore had grown up Ctesiphon, the winter residence of the Persian monarchs. The combined city had now for ages superseded Babylon as the capital of Chaldæa. Though repeatedly taken by the Romans, it was now great and prosperous, but helplessly torn by intrigue and enervated by luxury. The main quarter, with its royal palaces, was on the eastern side, where the noble arch, the _Tâk i Kesra_, still arrests the traveller’s eye as he floats down the Tigris.[283] On the nearer side was the suburb, Bahar Sair;[284] and towards it, as immediately accessible to attack, Sád now directed his march. Burân, the queen-mother, animated by the ancient spirit of the Sassanides, and swearing with a great oath that so long as the dynasty survived, the empire was invincible, herself took the field, with an army commanded by a veteran general, ‘the lion of Chosroes.’ She was utterly discomfited, and her champion slain by the hand of Hâshim. When he came to announce the victory, his cousin Sád kissed Hâshim’s forehead, in token of approval and delight; and Hâshim kissed the feet of Sád. [Sidenote: Sád besieges the western suburb of Medâin. Summer, A.H. XV. A.D. 636.] Sâd then marched forward; and, in reference to the vainglorious boast of the vanquished princess, he publicly recited this passage from the Corân:-- Did ye not swear aforetime that ye would never pass away? Yet ye inhabited the dwellings of a people that dealt unjustly by their own souls; and ye saw how We dealt with them; for We made them a warning and example unto you.[285]