Taprobana is the historical name for an island of the Antichthones (“opposite-world”), in the Eastern Sea, described by some Roman classic writers. Claudius Ptolemy described Taprobana in his Geographia, written about 150 CE, a relatively large island south of continental Asia and straddling the equator. Ptolemy also supplies a mass of information, including its coasts, the names of the headlands, rivers and seaport towns, the names of many cities and tribes in the interior, with coordinates. There have been primary subject of debates over Taprobana. Each succeeding generation has read vague descriptions of the island left by their predecessors, and wrangled over what their predecessors really meant. Some scholars consider it to be a wild misinterpretation of any one of several islands, including Sumatera and Sri Lanka. In the end, it is impossible to assign a single place with all of the qualities that have been labeled with the name Taprobana over the ages. After gathering abundance evidence, the author finally proofs that Taprobana is actually the Kalimantan Island (English: Borneo), an island at the geographic center of Maritime Southeast Asia.