Klingons have evolved in several stages over time. They used to be Russia, but then became Russia, but with some Zulu and Aztec thrown in.
The Cardassians used to be the North Koreans, now they are postwar Germany/Japan. Romulans used to be Nazis but now they are more like North Korea. The Ferengi are the Jews but without the stigma.
Alternate evil Earth is basically now everybody's Mexico.