Definition of "prorex"

Nay, pray you let him ſtay a greaterFits Menaphon, than warring with a Thiefe:Create him Prorex of Affrica,That he may win the Babilonians hearts,Which will reuolt from Perſean gouernment,Unleſſe they haue a wiſer King than you.

c. 1587–1588, [Christopher Marlowe], Tamburlaine the Great. […] The First Part […], 2nd edition, part 1, London: […] [R. Robinson for] Richard Iones, […], published 1592; reprinted as Tamburlaine the Great (A Scolar Press Facsimile), Menston, Yorkshire, London: Scolar Press, 1973, Act I, scene i