Two “poles” of Andean civilization developed over the centuries.?

Question

What salient features of the Andean environment caused this division?

Answer 1

huge mountains separating the coastal area from the rest of the continent = difficult to trade, intermarry with other groups; high desert (dry air, little moisture) making it difficult to grow crops

Answer 2

Civilization developed in South America in two important areas: coastal and montane.  The coasts are dry in western Peru but are blessed with a rich food resource in the oceans.  As one goes eastward, the Andes Mountains rise, and the peoples there exploited the different zones on the mountains in a kind of vertical mosaic effect.

There was trade between the two groups and with this contact came similar cosmological and mythological motifs.  

Tiwanaku and the Nazca developed in the south and the Sipan and Sican, Moche and finally Inca developed in the north.