Your question is very interesting and as far as I know it is a subject that is not touched much in the academy. First of all you must understand a historical problem that persists to this day in Peru: Centralism against Regionalism. To explain it in a simple way, both Flores Galindo and Quiroz agree that the particular Peruvian geography divided the country into various sectors, so that each sector had its own economic dynamics. As a consequence, historically, the regions had unequal developments and their own interests. Thus, there were two portions of the country that were practically not economically connected: the north (with the capital Lima) and the south, although the unity of the "north" is being discussed, the important thing for your question is the "south" whose unity is not discussed. . But what is the south? According to Flores Galindo, it is an area integrated by its economic ties that occupies the current departments of Arequipa, Cusco, Puno, Moquegua, Tacna, Ayacucho, Huancavelica, Apurimac, Madre de Dios and the Peruvian territories lost in front of Chile of Arica and Tarapaca. ; At that time it also extended to present-day Bolivia and the north of Argentina.Flores Galindo tells us that the bases of southern integration are not in a cultural or geographical homogeneity, but rather what he calls "economic circuits" that connect the economies of the different localities based on a certain economic activity (wine and "aguardiente ", minerals, wool, etc.) In such a way that the economic interests of the southern elites coincided and were capable of antagonizing those of the capital. So this is a region in the Peruvian historical context.Now, according to Basadre, Flores Galindon, Quiroz and others; the economic circuit of the south includes the audience of Charcas (Bolivia) and the north of present-day Argentina. Basically it consisted of the exploitation of mining and its transfer, both activities moved other sectors of the economy of the regions from the "obrajes" of Cusco to the alcoholic beverages produced industrially on the south coast. As Quiroz and Flores Galindo points out, the southern economy entered into crisis in the final period of the colony, one of its factors was the creation of the viceroyalty of the Rio de la Plata in 1776 (which included Charcas) and with the period of political violence initiated by Tupac Amaru II even the consolidation of independence only aggravated the situation. So the economic situation in the South before Confederation was pretty bad.

Now, politically and ideologically, post-independence Peru was a disaster. Peru one of the most interesting discussions that took place within the halls of the elites and the national congress was that of: federalism or centralism. For practical reasons, they used to opt for a centralist constitutional model but with a certain autonomy of the former intendancies, now departments (in the first three constitutions, 1821, 1826 and 1828). However, federalist thought was very influence throughout the country, including in Lima, for different reasons: admiration for the USA, disorder of the state, lack of information and rejection of centralism for being related to the old order. Basadre also told us that within this federalism there were two other currents of federalism usually from the south: supra-federalism (seeking union with Bolivia) and intranational (seeking union of only the south with Bolivia). Here is the base of the division of Peru into north and south.As I already mentioned, the southern economic circuit was severely damaged by the separation of the Audience of Charcas (today Bolivia) and later with the independence of Bolivia. In such a way that the interests of the ruling classes of the southern region favored a secession from Peru or a union of Peru with Bolivia. For example, the "plans of the prefects of the south" of 1826, the letters between the Bolivian president Santa Cruz (who was also part of the Peruvian government and army during independence and the first years of the republic) and his friends from the south of 1828, or the journalistic campaign of the Arequipa newspaper "Yanacocha" of the liberal Juan Gualberto Valdivia, among other conspiracies and publications.These divergent economic interests divided the Peruvian ruling class and fueled a regionalism in the south and a certain contempt of the Lima aristocrats for the southerners (the poems and racist insults against President Santa Cruz are famous). The conflict materialized after the military intervention of Bolivia in Peru during the period of disorder and civil war between caudillos. By means of article 4 of the Aid and Subsidy Convention, on June 15, 1835, through which the Bolivian intervention was agreed upon at the Peruvian request: "The peoples of Peru being entirely dislocated, and their political organization being one of the most essential objects , the Provisional President of that Republic, as soon as notice is given that the Bolivian troops have set foot on Peruvian territory, will convene an Assembly of the departments of the South, in order to establish the bases of his new organization and decide on its future fate." .The assembly was convened in Sicuani with the representatives elected in 1834 (former congress) and decided to create the southern Peruvian republic within the framework of the confederation. His rhetoric can be seen in the first articles of his constitution: "I. That the peoples of the South are convinced by long and sad experience that their association with those of the North, under the regime of unity, makes their organization difficult, if not impossible, and therefore more difficult the happiness that essentially depends on the form of government;"

So those are the foundations of the South Peruvian Republic. They were the consolidation of a regionalist project that pursued the economic interests of the ruling classes of the south. Reason for which the confederation had more support in parts of the south than even in parts of Bolivia, in Arequipa for example from conservatives like former Viceroy Pio Tristan or Archbishop Goyeneche to liberals like Valdivia or Lazo vehemently supported the confederation. Thus the southerners were economically integrated with Bolivia (remember its original name Alto Peru) and part of the south had intense cultural ties such as Puno or Cusco. In such a way that the original project according to Valdivia was to separate from the "Babylon of Ameria" (Lima) and form a state with their Bolivian brothers. However, for geopolitical reasons, the Confederation was formed and in the same way, for geopolitical reasons, the Confederation died shortly after. I hope what I wrote helps you, sorry for the writing but I don't have a PC.

Main sources:

Basadre: Historia de la republica y la multitud la ciudad y el campo en la historia del Peru.

Glores Galindo Arequipa y el sur andino (I recommend it if you know Spanish

Quiroz: Estructuras economicas y desarollos regionales de las clases dominantes.

Sobrevilla: Santa Cruz

Peter Klaren: EStado y nacion en la historia del Peru (this is in English)