Well, the way I understand it is that the ideal cut-off point for the Americas is theoretically 1492 (Columbus's 'discovery' of America), since the decision was made that only cultures prior to European contact could be covered, which is fair enough . However, the Aztec and the Inca didn't have any European contact at all until 1518 and 1526, respectively, so it seems illogical not to cover up to those dates (imagine if AW Rome was limited to a time period that excluded the late Roman Empire!). That's how I interpret it anyway. So we don't cover the actual Spanish Conquest, just the period up to it.

The post on the Aztec Market was taken from an Spanish eyewitness account, but it was written almost 50 years after the event - although Bernal Diaz wrote his book c. 1568, he is describing Tenochtitlán as he saw it when the conquistadors entered the city in 1519. The eye-witness testimonies of Spanish chroniclers are invaluable for description and understanding of pre-European-contact Aztec civilization. Does that make sense? :)