Final answer:
The Guarani people were originally from modern-day Paraguay and parts of Argentina, Brazil, and Bolivia. Their presence is especially significant in Paraguay, where their language remains official.
Step-by-step explanation:
The country that was previously inhabited by the Guarani people is modern-day Paraguay, along with parts of the surrounding regions in South America such as Argentina, Brazil, and Bolivia. The Guaraní are indigenous people who have a significant presence in these regions, particularly Paraguay, where Guarani is recognized as an official language alongside Spanish. They have a rich cultural heritage and a history that dates back well before the arrival of European colonizers.