The material on Banga is inspired by Smith's unique dreams and observations and the album's lyrics are a reflection of our complex world - a world that is rife with chaos and beauty. Both the album's musical structure and lyrical themes vary. Amerigo is based on imagining the voyage of Amerigo Vespucci to the New World in 1497 and Fuji-san is a rock song in tribute to the people of Japan following the 2011 Tōhoku earthquake and tsunami. This is the Girl is referred to as a classic ballad in memory of English musician Amy Winehouse and Nine is reportedly a birthday song for Smith's friend Johnny Depp. Constantine's Dream is a ten-minute-plus improvisational meditation and Smith has said [in the song] there are many questions. It questions the role of artists in our society. The questions are there, and they're not answerable questions. Maria is partially based on actress Maria Schneider and the song Smith calls the more emotional song on the record. Describing the song, Smith said: it's the one that looks back on a beautiful time and sort of encapsulates the [1970s] in a certain way for me. It's a nice little R&B song, but an emotional song.