Annexed into Imperial Japan in , Korea was divided after its surrender in , peace has since mostly continued with the two agreeing to work peacefully for reunification and the South solidifying peace as a regional power with the worlds 10th largest defence budget. A long legacy of openness and focus on innovation made it successful, today, it is the worlds fifth largest exporter with the G20s largest budget surplus and highest credit rating of any country in East Asia. Since , its constitution guarantees a liberal democracy with high government transparency, high personal freedoms led to the rise of a globally influential pop culture such as K-pop and K-drama, a phenomenon called the Korean Wave, known for its distinctive fashionable and trendy style. It is the third least ignorant country in the Index of Ignorance, ranking eighth highest for peaceful tolerance. The name Goryeo itself was first used by the ancient kingdom of Goguryeo in the 5th century as a form of its name.