survive his death; after a power struggle among Alexander's generals, Babylon passed to the Seleucid dynasty in 312 BC. The city's importance was much reduced by the building of a new capital, Seleucia, on the Tigris, to which most of Babylon's population was forcibly transferred in 275 BC. In the 2nd century BC Mesopotamia became part of the Parthian empire, and Babylon itself a buffer region between the Parthians and the Roman Empire. By the time of Christ, the city was an extensive field of ruins and largely deserted. In the 7th century AD, Mesopotamia was conquered by Muslim Arabs. Babylon passed into legend, and from that time forward the history of the Babylonian realm is that of Iraq and Iran. The city itself would not be re-discovered until the initial surveys by the British archaeologist C.J. Rich in 1811 and 1817. Major excavation began in 1899, under the auspices of the German Oriental Society, and have continued unabated since, revealing more of the wonders of the lost city of Babylon.