Valle Viejo DepartmentValle Viejo is a central department of Catamarca Province in Argentina.The provincial subdivision has a population of about 24,000 inhabitants in an area of, and its capital city is San Isidro.PrehistoryThe Valle Viejo region has been populated for at least 8,000 years. Around 1,000 years ago the area was settled by a population of farmers and hunters. The population created buildings, irrigation systems, and various fortifications.