Juan de Mendoza was a Spanish explorer and colonial administrator known for his role in the early exploration of South America. He was particularly active in the region that is now Argentina and Paraguay, where he contributed to the establishment of Spanish settlements and trade routes. Mendoza is best remembered for founding the city of Asunción in 1537, which became a significant center for Spanish colonization in the region. His efforts helped to expand Spanish influence in South America, paving the way for further exploration and settlement by other conquistadors.