A phrase referring to the age of mankind before the advent of the internet and/or before advanced data mining, search engines and online resources (especially Google, Wikipedia, etc.) made information widely available and convenient; i.e. when people had to do research manually via libraries, card-catalogs, paper books and reference materials such a Encylcopaedia.
Also jokingly referred to as "the before time, the long long ago" referencing the cultural memes of Star Wars and the 64th episode of South Park.
Well son, in "the before time", finding out answers to questions was a lot more difficult, it could take hours or even days to research topics and had to be done by physically going to a local library!