In 618 Emperor Li Yüan succeeded to the Celestial throne after the murder of the last of the Sui, Yang Ti. The High Progenitor, as he was entitled later, and his son Li Shih-min, the Grand Ancestor, were the joint founders of the T'ang dynasty, one of the greatest in the long history of China. Four years later, on 16 July 622, in the far-distant and arid coastland of Arabia, Prophet Muhammad abandoned his birthplace and fled to the oasis town of Medina. It was from there that his followers were to prey on the caravans of the wealthy merchants of Mecca, on their way to the Mediterranean markets of Gaza and Busra (Bostra). For commerce and civilisation in the Indian Ocean, these separate and unconnected events mark out a fresh beginning, a new order. The two geographical divisions of the great sea, the western and the eastern, meeting together in the massive under-water volcanic cliffs of the Java seas, were now gradually brought closer in a long chain of trans-oceanic trade. The administrative unification and the economic achievements of T'ang China, while they were responsible for the creation of new consumer demands and social tastes for luxuries within the limits of the empire, also led in the Far East to the emergence of a larger zone of Chinese cultural influence.