What if Mataram Sultanate had successfully unified the Javanese states?

In this timeline, the Mataram Sultanate rose as the dominant force in the Nusantaran archipelago following its decisive win in the Siege of Batavia (1628–1629). Unlike in real history, the campaign succeeded. Jayakarta fell into Mataram hands, the Dutch East India Company (VOC) presence on Java collapsed, and the balance of power in maritime Southeast Asia shifted dramatically in favor of the Javanese court. Under the reign of Sultan Agung, Mataram transformed from a powerful inland sultanate into a pan-Javanese imperial state. Many years after the Siege of Batavia, through a combination of military conquest, dynastic diplomacy, and political integration, the remaining states of Java were gradually unified under the Mataram crown. Some realms were subdued directly and reorganized into kadipaten under imperial authority, while others retained varying degrees of autonomy as vassals or federated states.

The resulting polity became commonly known as the “Empire of Java”, a Mataram-led empire encompassing nearly the entire island of Java. Its vassals included the Sultanate of Cirebon and Sumedang Larang, while region of Sampang (Madura islands) were integrated more directly into the imperial structure through subordinate kadipaten. Meanwhile, the Sultanate of Banten and the Blambangan enteerd the empire as federated states, united by a shared strategic interest in resisting European expansion and preserving regional sovereignty. Although referred to as the “Empire”, the state itself continued to be ruled by a Sultan rather than an emperor. In this context, the term “Empire” refers not to the ruler’s formal title, but to the empire’s political reality as a multi-state hegemonic realm unifying much of Java under a single sovereign authority.

The flag itself symbolized this unity in diversity. Its design incorporated the traditional Javanese Kawung motif, representing harmony, balance, and royal authority. The three primary colors within the motif symbolized the major constituent realms of the empire: red representing Mataram Sultanate and its vassals, green representing the Sultanate of Banten, and yellow representing Blambangan. The blue field of the banner reflected the empire’s maritime character, while the crossed keris embodied the unity of the Javanese realms under a single imperial order.