 Complete the following phrase:  Late Antiquity saw various indicators of Roman civilization beginning to decline, including urbanization, seaborne commerce, and total population. Only 40 as many Mediterranean shipwrecks have been found for the 3rd century as for the 1st. During the period from 150 to 400, with the intermittent appearance of plague, the population of the Roman Empire ranged from a high of 70 to a low of 50 million, followed by a fairly good recovery if not to the previous highs of the Early Empire. Serious gradual depopulation began in the West only in the 5th century and in the East due to the appearance of bubonic plague in 541 after 250 years of economic growth after the troubles which afflicted the empire from the 250s to 270s. Proximate causes of the population decrease include the Antonine Plague 165180, the 