When did Erlang come out? There clearly was interest in concurrency, otherwise, why make a new programming language (limbo or otherwise) just for the sake of it

When did Erlang come out? There clearly was interest in concurrency, otherwise, why make a new programming language (limbo or otherwise) just for the sake of it? Just because multicore wasn't common doesn't mean that concurrency wasn't important. Event loops have practically always been there on widely used OS's.