The Aceh Sultanate, officially the Kingdom of Aceh Darussalam, was a sultanate centered in the modern-day province of Aceh of Indonesia. It was a major regional power in the 16th and 17th centuries, before experiencing a long period of decline. Its capital was Kutaraja, the present-day Banda Aceh. Along with Mataram and Makassar, it has been referred to as one of Southeast Asia's major "gunpowder empires".