Peruvian
The proper adjectives are:KoreanPolishAlaskanBelgianSwedishFrenchRussianCubanPeruvianIndian
Large and varied are both adjectives. South would be an adjective if it were not part of a proper noun. Amazon is likely a noun adjunct here, but Amazonian would be a proper adjective.
Cuban and Peruvian are the proper adjectives for Cuba and Peru.
The proper adjective for southwest is "southwestern."
The proper adjective is Haitian.
The proper adjective for Portuguese is "Portuguese."
Vietnamese is the proper adjective for Vietnam.
No, old is not a proper adjective. A proper adjective is an adjective derived from a proper noun, such as Swiss cheese, Bolivian pottery, Chinese silk, etc.
The proper adjective for George is Georgian.
The proper adjective for Siam is Siamese.
Mayan is itself a proper adjective.
Freudian is the proper adjective for Freud.