Which peninsula is divided into two sovereign states, North and South Korea?

The peninsula divided between North Korea and South Korea is the Korean Peninsula.

It projects southward from mainland East Asia between the Yellow Sea on the west and the Sea of Japan, called the East Sea in South Korea, on the east. China borders it to the northwest across the Amnok (Yalu) River, while the Duman (Tumen) River separates its northeastern edge from China and Russia. Japan lies across the Korea Strait.

Korea was annexed by Japan in 1910 and remained under Japanese rule until Japan’s defeat in World War II. In 1945, the peninsula was divided into Soviet and American occupation zones near the 38th parallel. Two separate governments were established in 1948: North Korea and South Korea.

The Korean War began in 1950 and ended with an armistice in 1953, not a peace treaty. The Demilitarized Zone now runs across the peninsula near the former dividing line. The Korean Peninsula is not the Japanese Archipelago, Malay Peninsula or Indochinese Peninsula.