In 1852, at the fall of Rosas, the modern period began for the Parana. The river-population changed rapidly. It ceased to be exclusively creole. Basques, and later Italians, had settled upon the Uruguay ten years before, and they now spread along the Parana. In 1850 MacKann found fifty vessels, of 20 to 100 tons, belonging to Italians at Santa Fe. This wave of immigration coincided with the development of relations between the Parana and the port of Montevideo. From 1852 to 1860 Buenos Aires was isolated, and it remained outside the economic life of Argentina. Montevideo took its place. Urquiza's administration sought, in addition, to establish direct maritime communication between over-seas ports and the ports on the river: Gualeguy in Entre Rios, and Rosario in Santa Fe. Under a system of preferential duties (1857-59), which reduced the burden on goods carried by the river, Rosario grew rapidly, and between 1853 and 1858 increased its population from 4,000 to 22,700. The period from 1852 to 1860 was also the time when steam-navigation was developing, and this doubled the value of the river-route. From 1860 onward Buenos Aires was connected by regular services of steamboats with Rosario, Santa Fe, Corrientes, Asuncion and Cuyaba. On the upper Parana goods (timber, tobacco and oranges) were still carried by sailing boats between Corrientes and Apipe, where they stopped at the commencement of the rapids. Steamboats did not sail up the rapids of Apipe until 1868.[120] From 1850 to 1860 there were repeated explorations of the Salado and the Bermejo, as the interior provinces hoped to be able to find a connection with the vivifying artery of the Parana (voyage of Page on the Salado from Salta in 1855, and of Lavarello on the Bermejo in 1855 and 1863). [120] According to Rengger, sailing ships sometimes succeeded in crossing the Salto d'Apipe. In 1860 the entry of Buenos Aires into the Confederation re-established the normal condition of free competition between Buenos Aires and Rosario. From that time the life of the river reflects the advance of colonization in the Pampean region. The Parana became the highway for the export of cereals.