Oemar Said Tjokroaminoto (lahir di Ponorogo, 16 Agustus 1882) bukan sekadar politisi. Ia adalah seorang . Di indekosnya di Peneleh, Surabaya (sekarang dikenal sebagai Museum Rumah Peneleh ), ia mengajar murid-muridnya membaca, berpolitik, dan mencintai tanah air. Dari "kamar kos" itulah lahir:
Tjokroaminoto’s house in Surabaya was a melting pot of ideologies. He mentored various young students who would later lead Indonesia in wildly different directions, including: The future first President (Nationalism) Musso: A leader of the PKI (Communism) Kartosoewirjo: Leader of Darul Islam (Islamism)
Under Tjokroaminoto's guidance, Sarekat Islam became a driving force in Indonesian politics, advocating for greater autonomy, workers' rights, and social justice. His leadership helped galvanize a sense of national identity and unity, inspiring a generation of Indonesians to strive for independence.
