Taprobana was the historical name of an island in the Indian Ocean

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

. It was first reported to Europeans by the Greek geographer Megasthenes

Megasthenes

Megasthenes was a Greek ethnographer in the Hellenistic period, author of the work Indica.He was born in Asia Minor and became an ambassador of Seleucus I of Syria possibly to Chandragupta Maurya in Pataliputra, India. However the exact date of his embassy is uncertain...

 around 290 BC, and was taken up by Ptolemy

Ptolemy

Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...

. It may have referred to:

• Sri Lanka
  Sri Lanka
  Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
  
  , as in Ptolemy's map and clime
  Clime
  The seven climes was a notion of dividing the Earth into zones in Classical Antiquity....
  
  s
• Sumatra
  Sumatra
  Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...
  
  , as in the birthplace of Henry the Black
  Henry the Black
  Enrique of Malacca was a native of the Malay Archipelago who became a slave of the Portuguese explorer Ferdinand Magellan in the 16th century. Italian historian Antonio Pigafetta, who wrote the most comprehensive account of Magellan's voyage, named him "Henrich"...
  
  
• a phantom island
  Phantom island
  Phantom islands are islands that were believed to exist, and appeared on maps for a period of time during recorded history, but were later removed after they were proved to be nonexistent...
  
  

It is mentioned in the first strophe

Strophe

A strophe forms the first part of the ode in Ancient Greek tragedy, followed by the antistrophe and epode. In its original Greek setting, "strophe, antistrophe and epode were a kind of stanza framed only for the music," as John Milton wrote in the preface to Samson Agonistes, with the strophe...

 of the Portuguese

Portuguese poetry

-History:The earliest Portuguese poetry was produced in Galicia, today a Spanish province that shares some similarities with Portuguese culture. Like the troubadour culture in the Iberian Peninsula and the rest of Europe, Galician-Portuguese poets sang the love for a woman, that often turned into...

 epic poem Os Lusíadas

Os Lusíadas

Os Lusíadas , usually translated as The Lusiads, is a Portuguese epic poem by Luís Vaz de Camões ....

by Luís de Camões

Luís de Camões

Luís Vaz de Camões is considered Portugal's and the Portuguese language's greatest poet. His mastery of verse has been compared to that of Shakespeare, Vondel, Homer, Virgil and Dante. He wrote a considerable amount of lyrical poetry and drama but is best remembered for his epic work Os Lusíadas...

. Taprobana may be the Greek rendition of 'Thambapanni' (copper-coloured), the name of one of the ancient ports of Sri Lanka. It might also be a hidden reference to Tribhuvana, the great Hindu Triad. This could mean that Luís de Camões was saying that the Portuguese were going beyond the Earth, the Atmosphere and the Sky, in their epic quest, Os Lusíadas, as noted by Dalila Pereira da Costa.

It's also mentioned in Tommaso Campanellas Civitas Solis, which was written in 1602.