The Spanish were one of the most successful groups.  They were so successful because they brought over various diseases that the Native Americans were not immune to.  Another reason is because they had better weaponry like armors, guns, and cannons.  They also had animals like horses that the Native Americans had never seen before.  And the last reason is that they formed alliances.  Those are some of the reasons that the Spanish were so successful.

Disease the largest role of defeating the Native Americans.  The Native Americans had no immunity so they wiped out the entire communities in the Americas.  Altogether the diseases killed 90% of their population.  The Spanish brought the diseases without knowing.  They brought with them smallpox, influenza, measles, and other diseases.  

Another reason the Spanish were so successful was because of their weaponry.  The Spanish had armor, guns, swords, and cannons.  The Native Americans had never seen those types of weapons so they thought they were strange.  The Spaniards armor was the finest in the world so they were all but invulnerable when facing the Native Americans.  The Native Americans also thought that guns and cannons were thunder weapons.  Their swords were also sharper, stronger, and more deadly.  Also they were an easy target because of their elaborate clothing. 

Horses also had a part in the Spaniards success.  The Spanish rode horses and also had big dogs.  The Native Americans had never seen horses before, the largest animal in South America was the llama.  The llama did not install fear in the Spanish like horses did to the Native Americans.  The Spaniards horses also were covered with armor. 

The last thing that helped the Spaniards success was alliances.  Cortez was aided by a young Native American woman named Malinche.  She helped form alliances with Native groups that previously conquered by the Aztecs. 

My reasons helped state that the spanish were one of the most successful groups.   They were so successful mostly because of diseases.  The Spanish also had horses covered in armor.  Lastly the Spanish had better weapons.  Those are the reasons that the Spanish were so successful.