Lucrative export arrangements of this kind did not last, however. Early in the 1st century A.D., as Italian peasants and wide-eyed provincials flocked towards Rome in search of work and a higher standard of living, the population of Italy's cities soared. The Italian farmlands were sorely pressed to gather enough produce for local consumption, let alone grow a surplus that could be exported. Meanwhile, the most productive Gallic mines were placed under imperial management, so the earlier exchange of Italian wine for Gallic metals became unnecessary. The Gauls now turned to the wine-growing districts closest to them, in northern Spain. Since hardier varieties of vine now were being cultivated both there and in northern Italy, viticulture steadily moved northward. Wine production in Gaul itself rose dramatically, so that by the time of the emperor Nero (reigned, A.D. 54-68) the direction of the Italian-Gallic wine trade was in full reverse.