How was Burma (now Myanmar) known to ancient Indians?

Suvarnabhumi is a Sanskrit term meaning the Golden Land or Land of Gold, coined by the ancient Indians which refers broadly to Southeast Asian region across Gulf of Bengal and Eastern Indian Ocean, Lower Burma, Lower Thailand, Lower Malay Peninsula, and Sumatra. Although it seems to cover vast region in Southeast Asia, it is generally accepted that the name Suvarnabhumi was first used to refer more specifically to Lower Burma.