Altogether, "India" could denote any land east of the
Nile and west of Cathay. It is not surprising then that the term "India" was often meant to conjure the idea of vast eastern, non-Christian space.
Hamilton points out that earlier writers had already subdivided Middle India in three types of Ethiopians, one of which being Indians, exemplified by Gervase of Tilbury (1150-1220) in his encyclopedic Otia Imperiali (b. 1220).
According to Armondo Cortesão, the term three Indies appeared for the first time in a manuscript by Guido of Pisa (c. 1118). The concept may thus have been fairly new when the letter of Prester John was written, although the use of India Major (or Magna) an India Minor was certainly much older. The tripartite division of India enjoyed thereafter a wide acceptance... The precise geographical coverage of each part, however, is never fully defined. From one author to another, their extent is somewhat variable. Occasionally, they can even be contradictory. This fact notwithstanding, Lesser India would normally embrace Mackran and the coast below the Indus as far as some point immediately north of Malabar. Greater India used to include the southern half of the Hindustan Peninsula, extending then eastwards to the Ganges and beyond without any clear end. Finally, Middle India was almost unanimously thought to cover eastern Africa.