The last political vestige of the Gengis Khan's empire (the Crimean Khanate) was still around when the USA was founded.

They're not considered ugly, it's just that double eyelid is usually preferred. There are sex symbol women with single eyelids like 가인 Ga-een, or 김연나 Kim Yeonna. The latter is a skater but still considered smoking hot.

Asia remains more racist/nationalist than Europe after World War II. Europe felt a sense of needing to ensure a world war would never happened again.

Japan attacked China multiple times after the Meiji restoration.

Japan never lost its bushido spirit: during WWII, it intended to fight to the death, and expect no mercy from its enemies.

Japan committed atrocities against China during the war, including dropping cholera infested flies (after vaccinating its own people), and malaria infected mosquito's.