APL from 1966, I believe, is the key lang for array programming.
And statistical languages like S from 1976 come to mind: https://en.wikipedia.org/wiki/S_(programming_language)
At a quick glance, it seems PDL is just a variation on S.
For my understanding, the numpy syntax most closely resembles what would be possible in matlab. And matlab again seems to have roots from Fortran. Thanks to that, young folks nowadays can switch so easily between Fortran and Numpy, the syntax and call structures can easily be made to almost fit to each other.
i think you meant "competition" here :)
(in polish, my native language, it's "konkurencja", but it's a "false friend of the translator"; i'm guessing you're in a similar boat)
Then Travis started Numpy which somehow magically was backward compatible with both numeric and numarray - and managed to get the community united again.