What language was spoken in ancient Korea?

The official language of ancient Korea was Korean, but the written language was Chinese characters.

Proverbs (Korean characters) were invented by King Sejong in 1443. Compared with the geographical location of North Korea, Seoul, the capital of South Korea, has been the capital of Lee's Korea (later renamed the Korean Empire) since 1392, so South Korea's "standard Korean" is closer to the official standard language before the division of the Korean Peninsula. At that time, the official books of North Korean officials, nobles and upper class still used Chinese, so proverbs failed to become official texts. At the end of World War II, North Korea completely abolished Chinese characters, and all Korean words were spelled with proverbs. South Korea once abolished Chinese characters, but due to the inconvenience caused by pinyin, it resumed the basic education of Chinese characters to distinguish the different meanings of homophones.