Well, my theory was that the Teocalli were being used to move substantial amounts of mana in order to raise the magic level in a certain area high enough to summon a very powerful spirit-form. Essentially, Gestalt could form through blood transfusion, making a very powerful "summoner" and then with a large enough sacrifice (a dragon, maybe) and enough mana (hence the Teocalli) to summon one hell of a Blood spirit.
Additionally, I speculated that the teocalli rituals were being used as a network to find one of the Loci.
