South Asia also has a pattern of peninsulas, islands and surrounding seas. No one did establish an unified government over Thailand/Ayutthaya, Malacca, Majapahit, Burma, Sri Lanka, sundry coasts of Hindustan etc... to shut down seafaring by central fiat.
Yet neither the Malays nor the Arabs did discover the passage around Cape of Good Hope. Even when the Portuguese showed them it was possible, none of them sailed back to Atlantic... not on their own ships, and not even copies of Portuguese ships.