Where did the name Paraguay come from?

The name Paraguay comes from the Guaraní words "pará", meaning "a river" or "sea", and "guay", meaning "people", therefore "river of the people". The name was first applied by the Spanish explorers of the 16th century, who coined the term "Payagua", or "Pariaguai", for the Guaraní-speaking peoples who lived in the area of the Río Paraguay.