Reading Leff made me think: how would history be changed if the Northeast had seceded from Brazil?
in what period? 2000s, 20th century, 19th century?
Would, as Leff suggests, the region have been better able to develop independent of Rio de Janeiro (or Brasilia)?
Maybe, and that's a big maybe. The region is the poorest in the country, needing money from the more economically developed regions to function (since the discovery of gold basically). It is the region of the oligarchs with the oldest kleptocratic families residing, it is the bastion of this cancer. For that simple reason, the answer is no. Now assuming that the region manages to deal with these oligarchies (which is difficult because they are well entrenched). Honestly, I tend to think it will be worse than the OTL. It will be a weak nation economically speaking with a neighbor who wants their territories back. It´s going to have to spend a lot on weaponry to stay competitive.
Also, why did the Northeast not succeed in seceding from Brazil and what would have had to change for a successful secession?
You have to change the world to be honest. The fall in the northeast is due to the discovery of gold in the southeast and the creation of other sugar producing markets, which reduced the rate of profit. With the discovery of gold, the region ceased to be the most populous and lost importance. In the long run, the southeast remained the economic center and the south became the military center due to the wars in the Plata basin. The northeast kind of existed, with a corrupt and incompetent elite sucking up everything that was produced in the region and with the most productive people heading towards the southeast to try their luck.
This is demonstrated in the wars of independence, while the south surrendered in the war of separatism, the region achieved all the conceptions demanded by the revolutionaries and its troops were absorbed by the army (maintaining its appropriate rank). In addition, we have certain groups/states that were loyal to the crown in the Northeas, such as Bahia, which managed to keep the rest behaved. The state of bahia was not really considered northeast. When the state really fell into real decline it was added to the northeast region but before that it was seen more as part of the southeast. In addition we have the apathy of the local population. Revolts were usually carried out by elites who abused the local population and thus had little local support. With the population being kind of apathetic to the idea of independence. The government sent the army to execute the rebel elite, put some local loyal noble in conjunction with a federal government supervisor (who was usually competent which improved how the region was managed). It was relatively easy to deal with these revolts. All these factors make independence difficult.
If we take the revolts in the most chaotic period. The uprisings of the Regency Period we have:
Cabanagem, in the Province of Grão-Pará (1835 – 1840);
The main causes of the revolt were Political and territorial disputes, motivated by the elites of Grão-Pará, the provincial elites wanted to make political and administrative decisions in the province, neglect of the regency government towards the inhabitants of Grão-Pará,the cabanos, for their part, wanted better living and working conditions. The Elites took advantage of popular dissatisfaction to revolt the populations against the regency government. Cabanagem left a carnage of more than thirty thousand dead, almost 30 to 40% of the population of the province.
Farrapos War (or Farroupilha Revolution), in the Province of Rio Grande do Sul (1835 – 1845);
The revolt was mobilized by the large landowners of Rio Grande do Sul, dissatisfied with the high taxes levied by the imperial government on their products. Therefore, they found that separation and the republic would be a way to obtain commercial and political freedom. Enslaved blacks were also recruited to fight, under the promise of freedom, in case of victory in the war against the empire. The Farrapos War was promoted by the ruling class from Rio Grande do Sul. Consisting of ranchers who were the owners of large rural properties, cattle and enslaved blacks. Outraged by the high territorial taxes, in addition to high taxes on beef jerky, leather and tallow exports. Estanceiros protested, as beef jerky from Rio Grande do Sul had to pay 25% taxes while Uruguayan jerky only paid 4% to be sold in Rio de Janeiro. The revolution was favored by the militarized character of society in Rio Grande do Sul, organized in the midst of struggles such as the dispute for Colonia do Sacramento, in the 18th century.
In 1845, the rebels accepted the peace proposal offered by the government. The Poncho Verde Treaty established the incorporation of farroupilha officers into the imperial army, liberation of slaves who had fought alongside the farroupilhas, return of lands that had been taken from the rebels, reduction of taxes in that province and strengthening of the Provincial Assembly.
Revolt of the Malês, Province of Bahia (1835);
The Malês Revolt, represented a quick rebellion organized by slaves of Islamic origin ( especially from the Hausa and Nagô ethnic groups), who mainly sought religious freedom, however it was repressed by imperial troops. the Malês, warrior men, daring and educated, had as main objectives to free the slaves of Islamic origin, exterminate the Catholic religion and establish an Islamic republic. They were killed and islam was forbidden.
Sabinada, in the Province of Bahia (1837 – 1838);
The reason for the revolt was the dissatisfaction with the province's lack of political and administrative autonomy, since in the eyes of the rebels, the regency government was illegitimate. As well the mandatory recruitment imposed on Bahians due to the Farrapos War. The intention of the rebels was only to constitute a Republic of Bahia until D. Pedro II reached the age of majority. Therefore, their dissatisfaction was strictly directed at the regency government and it was not a war for independence. The state was loyal to the crown. The uprising had the support of the urban middle classes, mainly military officers, civil servants, liberal professionals, merchants, artisans and a portion of the poorest layers of the population. With the help of the army and local militias the government forces regained the rebellious regions. Therefore, even internally, part of the troops refused to rebel and attacked the rebels.
Balaiada, in the Province of Maranhão (1838 – 1841).
The revolt emerged as a social uprising for better living conditions and had the participation of cowboys, slaves and other disadvantaged people. It was defeated without major complications.
As you can see, revolts normally did not have the mass to win against the central government, and those who did actually wanted certain privileges or rights.