Who did the Spanish began to explore lands north of Mexico?

The Spanish began to explore lands north of Mexico primarily due to the quest for new territories, wealth, and the spread of Christianity. Notable explorers such as Francisco Vázquez de Coronado and Hernán Cortés ventured into present-day southwestern United States and other regions in search of gold and other resources. Their expeditions were part of a broader Spanish effort to expand their empire and influence in the New World during the 16th century.