Growing up he was influenced by Brazilian musicians, listening to the radio. He was influential in the Tropicalia movement in the 1960s but began to move away from the genre due to the military dictatorship in Brazil (1964). - led to his experimentation with music - instruments & style  

The Tropicalia was one of the most important cultural revolutions in Brazilian culture. (according to Tate) It was a creative movement that originated in the late 1960’s, covering many disciplines but was most known as a music movement. 

Jill Drower describes Tropicalia as ‘a creative explosion and a political movement wrapped into one’.

Tropicalia was specifically coined by artist Helio Oiticica when describing his exhibit in Rio de Janeiro in 1967, and was also famously used as an LP name from a collection of experimental Brazilian musicians in 1968.

During the 1950s and early 1960s there was optimism amongst Brazil as new president Juscelino Kubitschek had just been elected. There was promise for stability in a country that had been unstable for decades. At this time artists were blossoming into new creative approaches with interactive art and abstraction.

But in the late 1960s the western world was also going through a cultural change, the US was at war with Vietnam.

But a military coup backed by the USA brought an oppressive right wing government into power. The US began cracking down on the rise of socialism within Brazil, the military dictatorship censored and froze certain kinds of artistic production, especially that which opposed the regime. The dictatorship lasted 21 years, had 5 military mandates and instituted 16 new institutional acts (laws).

But in doing so sparked an ever bigger revolt within the Brazilian leftist community, leading artists and musicians to fight for freedom of expression through creativity. But at the same time Rock music had begun to enter Brazil from North America, many Brazilians saw it as a threat to Brazilian culture, and were also critical of the role of the US government supporting the dictatorship. Some artists even took part in a march against the electric guitar, which they saw as a symbol of american imperialism. (source: https://medium.com/@ruoso/to-understand-brazilian-music-the-march-against-the-electric-guitar-8e7ed615724)

Tropicalia sought to unify Brazilian culture and stand against being white washed and silenced by the US government. This development of the movement was instigated by Caetano Veloso, who created a manifesto for Tropicalia in the form of the album “Tropicalia: ou Panis et Circencis”

Tropicalism completely redefined Brazilian music, which up until this point had its peak with the jazzy samba genre Bossa Nova. Tropicalism extended into fashion, defying the norms of masculinity and morality.

Sources:

https://www.tate.org.uk/art/artists/helio-oiticica-7730/story-helio-oiticica-and-tropicalia-movement#:~:text=Tropic%C3%A1lia%20was%20a%20creative%20movement,regime%20of%20the%20military%20government.