primarily Ptolemaic work. Inheriting the trade of ruined Tyre and becoming the centre of the new commerce between Europe and the Arabian and Indian East, the city grew in less than a generation to be larger than Carthage. In one century, Alexandria had become the largest city in the world and, for some centuries more, was second only to Rome. It became Egypt's main Greek city, with Greek people from diverse backgrounds. The Septuagint, a Greek version of the Tanakh, was produced there. The early Ptolemies kept it in order and fostered the development of its museum into the leading Hellenistic centre of learning (Library of Alexandria, which faced destruction during Caesar's siege of Alexandria), but were careful to maintain the distinction of its population's three largest ethnicities: Greek, Egyptian and Jewish. By the time of Augustus, the city grid encompassed an area of , and the total population during the Roman principate was around 500,000–600,000, which would wax and wane in the course of the next four centuries under Roman rule. According to Philo of Alexandria, in the year 38 AD, disturbances erupted between Jews and Greek citizens of Alexandria during a visit paid by King Agrippa I to Alexandria, principally over the respect paid by the Herodian nation to the Roman emperor, and which quickly escalated to open affronts and violence between the two ethnic groups and the desecration of Alexandrian synagogues. This event has been called the Alexandrian pogroms. The violence was quelled after Caligula intervened and had the Roman governor, Flaccus, removed from the city. In 115 AD, large parts of Alexandria were destroyed during the Kitos War, which gave Hadrian and his architect, Decriannus, an opportunity to rebuild it. In 215 AD, the emperor Caracalla visited the city and, because of some insulting satires that the inhabitants had directed at him, abruptly commanded his troops to put to death all youths capable of bearing arms. On 21 July 365 AD, Alexandria was devastated by a tsunami (365 Crete earthquake), an event annually commemorated years later as a "day of horror". Islamic era In 619, Alexandria fell to the Sassanid Persians. The city was mostly uninjured by the conquest and a new palace called Tarawus was erected in the eastern part of the city, later known as Qasr Faris, "fort of the Persians". Although the Byzantine emperor Heraclius recovered it in 629, in 641 the Arabs