Unitary and Federal
The first decades as an independent country were tumultuous, even when the wars of Independence had not ended, strong conflicts arose before the hegemony of the Unitarians, which was opposed by the federalism advocated by the eastern José Gervasio Artigas. The fights between Unitarians and Federals led Argentina to a long series of bloody civil wars between factions and provinces (1820 – 1861); Also, the Portuguese-Brazilian occupation of the Eastern Province unleashed a War with the Empire of Brazil (1825 – 1828). Regarding the territory, in 1826 the province of Tarija it was incorporated into Bolivia and, as a result of the Preliminary Peace Convention that tried to end the war with Brazil, in 1828 the Eastern Province was declared independent, adopting the name of the Eastern State of Uruguay. 
In 1829 one of the most important landowners in the province, Juan Manuel de Rosas, assumed the governorship of Buenos Aires, exerting a great influence over the entire country. Thereafter and until his overthrow in 1852 He retained power in an authoritarian way, harshly persecuting his opponents and practicing censorship, although he had the support of broad sectors of the people and the Buenos Aires upper classes. During the Rosismo, as a country located in South America according to POLITICSEZINE.COM, nickname by which this stage of Argentine history is known, Buenos Aires livestock activity grew enormously, exports and some industries in the interior that were protected thanks to the Customs Law. Rosas opposed the national organization and the sanction of a constitution, because this would have meant the distribution of customs revenues to the rest of the country and the loss of Buenos Aires hegemony. 
In 1852 Rosas was defeated in the Battle of Caseros by the Big Army, an alliance between the provinces of Entre Ríos and Corrientes, the Colorado troops from Uruguay and others from Brazil. The alliance was headed by the federal anti-Rosista Justo José de Urquiza, Governor of Entre Ríos, who assumed the provisional presidency. This provisional bogierno lasted until the promulgation of a Constitution in 1853, which adopted a federal regime; but this was rejected by the province of Buenos Aires, which separated from the Argentine Confederation, due to which it had to establish its capital in the City of Paraná.
Later, the governor of Buenos Aires established a decree that affected the trade of the Confederation: it established that the products of the interior would be treated in Buenos Aires without any difference with foreign merchandise. Faced with this action, in May 1859, the Congress of the Confederation authorized Urquiza to resolve the question of national integrity through peaceful negotiations or war, as circumstances advised. On October 23, 1859, the Confederate army and the Buenos Aires one faced each other in Cepeda, and Urquiza obtained the victory.Despite the union of Buenos Aires to the Confederation, the conflicts between them did not end until the Battle of Pavón took place. (1861), in which the Confederate provinces surrendered to the Buenos Aires troops under the command of Bartolomé Miter, after which the existence of two separate states was ended and Miter assumed the presidency of the unified nation. 
Second half of the 19th century
In 1865 Argentina gets involved in the War of the Triple Alliance with Paraguay, when this country occupies the city of Corrientes, after Miter denied the passage of Paraguayan troops through Argentine territory in the direction of Brazil and Uruguay. As a consequence of these actions, the Triple Alliance Treaty between Argentina, Uruguay and the Empire of Brazil was signed.  It was an unpopular conflict in Argentina and the troops that were sent were few. Paraguay would be finally defeated in 1870, dying a large part of its male population. For Argentina, the end of the war territorially meant the consolidation of the limits in the northeast, since the border was set on the Pilcomayo, Paraguay and Paraná rivers, and the area north of the Pilcomayo river up to the river was accepted to arbitration. Green.
Between 1878 and 1884 the so-called Conquest of the Desert took place, which consisted of a series of genocidal military incursions against the Mapuches and other indigenous peoples to annex the Pampean and Patagonian territories where they lived to Argentine territory, promoted by Julio Argentino Roca. The success of the measure led to a similar action in the Gran Chaco region, which in 1884 suffered a military action also aimed at annihilating the Indians and fully occupying the territory.
The so-called Conservative Republic organized a successful and modern agro-export model, oriented to the production of meat and grains destined for the European market, this economic model generated a strong concentration of wealth in few hands and the exclusion, overcrowding and segregation of the working class. The economy reached high levels of growth that attracted a large flow of immigration. The Argentine population, which represented 0.13% of the world population in 1869, would go on to represent 0.55% in 1930, a proportion in which, approximately, it would stabilize since then. 
The prosperity of the economy fueled the growth of the middle class, the creation of modern political parties such as the Unión Cívica Radical (UCR) and the Socialist Party (PS), and a broad development of trade unions. Among the most influential presidents of the period are Domingo Faustino Sarmiento (1868 – 1874) and Julio Argentino Roca (1880 – 1886 and 1898 – 1904).