Jarre used the hungarian folk song Tavaszi szél vizet áraszt (Spring wind blows water) as the main theme for the music.
https://www.youtube.com/watch?v=Padd4q5ZqzU&ab_channel=Guly%C3%A1sFerenc-Topic
Freddie Mercury also sang this song, when he performed in Hungary in 1986.
https://www.youtube.com/watch?v=w24Z6SzYO_o&ab_channel=MAZOLIKA01