Inter-regional teammates in CS

So just got into CS and in a couple of highlights/clips show teammates(most of them also valorant players) from both EU and NA play together on the same team. How does this work?
(Examples include Mixwell,Zews(BR),s1mple all played on NA teams). Is there a lot of travel involved?

I also have this doubt !! How ?

And like that, there are so many EU/KR players in NA based teams in league

CSG OMEGALUL

mixwell, simple, moved to NA for a bit to play on NA teams, and some BR teams moved the whole team to play in NA against better competition