Balhae's Provincial System: 5 Capitals, 15 Prefectures, 62 Districts

Around the reign of King Seonwang, Balhae established a provincial administrative system dividing the realm into 5 capitals, 15 prefectures, and 62 districts. This efficient governance of a vast territory laid the foundation for Balhae to be called the 'Prosperous Kingdom of the East.'