Although it's not obvious from my Zonal Overview, the African continent is also represented in the table at the center of that post.
Africa first received formal recognition in the FIDE hierarchy when zone 11, the 'Afro-Mediterranean zone', was established in the mid-1970s. A few years later it was split into zone 11, the 'Mediterranean zone', and zone 12, the 'African zone'. In the early 1980s, the African zone was split into zone 12, the 'North and West African zone', and zone 13, the 'East and Central African zone'. When FIDE moved to the continental structure in the early 1990s, Africa was assigned three separate zones within the African continent.
The various African zonals and continental championships (designated as 4.0) are shown in the following table.
I haven't been able to locate details of certain events -- most notably the zonals which should have taken place before the 1990 and 1993 interzonals (cycles 15 and 16 in the table) -- and I suspect the African players were nominated by the zone presidents. I'll clarify this as soon as I can.
Note: For the previous post in the 'Chess in Africa' series, see Chess in Africa - Titled Players.