In one of the first reviews of Euclides da Cunha's posthumous À margem da história (1909), Arthur Guimarães de Araújo Jorge, a poet, diplomat, and regular contributor to the Revista Americana, praises the work as an exceptional piece that confirmed the talent Euclides exhibited in Os sertões (1902), and lamented that it was “fatally doomed” to the public's indifference. Euclides's unique style and impressions of Brazil's most acute problems went unnoticed by the local intellectual class used to commenting on a narrow range of topics and genres. “Não se galhardeiam idéas no reino do palavreado” [Ideas are not blatantly exhibited in the realm of idle talk], observed Araújo, explaining this unenthusiastic reception. Warmer recognition came later, with literary critic Péricles Moraes's essay reviewing major contributions to an Amazonian corpus in 1935, commending Euclides's original vision of the territory and aesthetics as a reference for everything that was thereafter “thought and written about such a portentous region”.

Euclides's fascination with the Amazon began in the backlands. After the success of Os sertões, he aimed to undertake a similar project in the northern region of Acre, inspired by both a vision of science as a path for the country's development and his desire to further his role as an intellectual after the success of his saga on Canudos. The political scenario could have not been more auspicious. After a long-lasting conflict over the allocation of contested lands in Acre (1899–1903), Brazil and Bolivia resolved their disagreement with the signing of the treaty of Petrópolis (1903). Promptly Peru opposed the settlement, arguing that Bolivia had yielded lands that did not belong to her.