Data modelling has been around for an awfully long time
This is the IDMS rubber stamp I used, starting in the late 1970's, to do data modelling.
Data modelling tools in those days consisted of: a good supply of blank paper, one pencil, and one rubber stamp with inkpad.
I had a recruiter ask me the other day how long I've been doing data modelling. Is it fair to say twenty-five years? After all, I held other positions in the interim -- database tech support, database software sales, data administration, project management...
"In fact," I said, "even if I had been modelling fulltime, meetings alone would account for ..." but she didn't want to hear that kind of crap, so I estimated an equivalence, and said ten years.
Here's an example of an IDMS database diagram, borrowed from Neal Walter's site at http://ItDoesMoreStuff.com (look at the capitals in the CamelCase domain name; this site offers IDMS computer based training) --
Notice the many-to-many relationship between JOB and EMPLOYEE through the EMPOSITION "junction" record, and the EMPLOYEE hierarchy through the STRUCTURE record, using REPORTS-TO and MANAGES sets. Pretty much how you'd do it today in a relational database, using Foreign Keys rather than set pointers.
For anybody interested, here's an IDMS history (an archive.org snapshot of an Australian IDMS User Group site), including a fascinating account of the rise and fall of Cullinet, the first software company listed on the New York Stock Exchange. It is rumoured that Oracle later achieved its growth largely on the desire of Larry Ellison to bury Cullinet, but I think Cullinet did a pretty good job of screwing up all on their own.
I worked for Cullinane Canada from 1979 to 1980.