The concept of "generations" as defining peer groups is broken

This thread made me curious how other countries aside from the United States define the generations. I was going to ask here but decided to start my own thread since it is NOT what the OP asked about:

https://boards.straightdope.com/t/do-other-countries-use-baby-boomer-and-generation-x-or-what-do-they-describe-the-generations-as/1004914