Sabana

Hello everyone,
recently I found a text regarding the country, Singapore used to be called Sabana by Pteolemy, a Greek geographer during the 2nd century. I am wondering what is the meaning or origin of naming this place Sabana. Has anyone got the slightest clue or any guesses? Thanks in advance. =)

To be taken with a grain of salt, since I’m not a scholar.
Singapore is not an English word, but the adaptation to English of a native word. Likewise, Σάβανα is what the ancient name of the place sounded to Greek ears.