Spain wanted glory and gold, and because they had let the Conquistadors establish settlements in the Americas they asked the Conquistadors. The Conquistadors promised Spain 1/5 of all the gold they captured.
We will give you 1/5 of all the gold we capture.
We want glory and gold!
A conquistador named Hernando Cortes was eager to win riches and glory, he had heard rumors about very wealthy Native Americans. So in 1519 he set out for Mexico in search of gold.
600 soldiers, check, 16 horses, check
Welcome them as guests
Cortes arrived at the Aztecs, and Moctezuma, the Aztec emperor was told reports of a large floating house (ships) filled with white men with beards. Moctezuma decided to welcome them as guests.
There are large floating houses at sea!
When Cortes arrived he took advantage of Moctezuma's invitation. He got valuable information about the Aztecs from a women called Doña Marina.
At first he was nice to the Aztecs later however he made the Emperor a prisoner in his own city.