Yeah easy_install, which theoretically worked (kinda), but alongside pip there was also the overall pypa effort (both marketing and technical) to make the whole thing work e.g. update or even fork the more abstruse projects such that they could actually be installed via pip. IIRC that was the primary reason for Pillow forking PIL.
Initial pip release was also 2011. Now I wonder what I used pre-pip?!
edit: easy_install, doh!