What's is the relationship between banks and crypto platforms?

I was going to say crypto exchanges but used platforms instead as I'm not sure if every platform you can transfer fiat money to is actually an exchange .

So, you need to transfer money from fiat to crypto space(an exchange or some crypto platform that accepts fiat). You can then obviously exchange your fiat for crypto to get the ball rolling.

So I'm wondering what the relationship and technology is between banks and exchanges, how are you able to transfer fiat into crypto space in the first place.

Did the exchanges and banks get together at some point to make an agreement and what technology is used to do this. How does the banking system interface with the crypto blockchain for example and what rules and regulations govern it all?