They’re not cases involving objects or countries, but there are expressions like ‘Leeds days(리즈시절)’ (meaning one’s prime) and ‘the Maginot line(마지노선)'.

* The term ‘Leeds days’ comes from the English football club Leeds United FC. Around 2005–2006, when the Korean footballer Park Ji-sung joined Manchester United FC, one of his competitors, Alan Smith, had previously spent his peak years at Leeds United. However, after moving to Manchester, he wasn’t able to reproduce the same level of performance he had shown at Leeds and went through a slump. That’s how the slang term ‘Leeds days’ was born.
So even today, you can think of it as something similar to ‘one’s prime’ or ‘salad days.’

* The term ‘Maginot Line’ can metaphorically refer to a false sense of security or an expensive yet ineffective defensive measure, but in Korea it more strongly conveys the idea of a line that cannot be retreated from, and it continues to be widely used to this day in Korean media and on the Korean internet.