Lennon wrote the song as a veiled account of an extramarital affair he had in London. When recording the track, Harrison chose to add a sitar part after becoming interested in the instrument's exotic sound while on the set of the Beatles' film "Help!", in early 1965. "Norwegian Wood" was influential in the development of raga rock and psychedelic rock during the mid 1960s. The song also helped elevate Ravi Shankar and Indian classical music to mainstream popularity in the West. Many other rock and pop artists, including the Byrds, the Rolling Stones and Donovan, began integrating elements of the genre into their musical approach. "Norwegian Wood" is also recognised as a key work in the early evolution of world music.