Anthony Sattin in The Guardian:
The city of peace was born out of blood, created following one of the perennial bloodlettings between Sunni and Shia Muslims that have occurred with depressing regularity since the untimely death in 632AD of the prophet Muhammad. The previous rulers of the Arab world, the Sunni Umayyad caliphs, had been based in Damascus. But with the ascendancy of the Abbasids in the 8th century, their Shia leader, al-Mansur – the Victorious – decided to create a new capital on the Tigris. The site was an inspired choice as it has good access via the Mesopotamia river system and along the Persian Royal Road to the markets of the Silk Road, the Arab Mediterranean and the Indian Ocean. The cliche that history repeats itself may well have been coined in this city for few places on earth have enjoyed such relentlessly inevitable cycles of prosperity, cultural outpouring and descent into bloodletting. Perhaps no one has expressed this duality better than al-Mansur's grandson, Harun al-Rashid. Harun is famous for being the caliph of The Arabian Nights, and is celebrated for having overseen one of the most glorious of all the city's booms. While the empire was run by the grand vizier, Harun filled his magnificent palace with scholars and poets, his gold goblet with Shirazi wine and his bed with some of 40 or so gorgeous courtesans from his harem. Marozzi weighs this image against another side of the pleasure-loving aesthete, for Harun, who made the pilgrimage to Mecca eight times, was also capable of leaving his friends briefly at a banquet to go and behead two girls caught in bed together. When he returned with their jewel-bedecked heads on a platter, one of his courtiers recorded that he “found this a horrific sight”.
More here.