Sheng started as a hybrid slang spoken in Nairobi's Eastlands in the 1960s, mixing Swahili, English, and vernacular languages. By the 1990s, musicians like Kalamashaka and Gidi Gidi Maji Maji were rapping in it, and Sheng became the language of Kenyan hip-hop. Gengetone took it further, making Sheng the default language of youth pop culture. Now it's spoken across class lines, taught in schools, and used in advertising. What began as a code to exclude outsiders became the sound of modern Kenyan identity.