C and later on C++ just got widespread due to UNIX's adoption at the enterprise, before that, there were quite a few systems programming languages around.
Of course, youngsters nowadays tend to think only C and C++ play on that league.
Interesting. Which ones in particular were popular? And what do you consider a "systems programming language"? As I understand it, a systems programming language is a language that can be used to implement an operating system. C was the first high-level language to be used in this way.
Of course, youngsters nowadays tend to think only C and C++ play on that league.