There is growing in the Aztec Empire a movement which is highly mystical, and which preaches the end of human sacrifice, as well as the introduction of new ways. The old order has been engaged in ruthlessly repressing it, and building up a larger army of the best and fiercest archers in the world.
The Aztec Empire is also plagued by ceaseless raids and a long running conflict against a mountain empire of Inca descendents. They also, quietly, pay heavy tribute to the Viking republics, who control the sea.