Hegel made various references to Urcommunism, which was the society before the "invention" of private property. Which was somewhat of a very wishful interpretation of the past. Anthropology would not be very happy with his interpretations. Also Urchristianity, and the very first christian communities and principles were an inspiration. Marx' Communism draws many parallels to this (intentional).

Ideologically, there were other socialists before Marx, upon which he drew, but who weren't scientific, as Marx would argue.