Only what was in Ctesias’ work Indica (Ctesias).
The text only survives in quotations from later authors, and in a summary by Photius:
Photius’ excerpt of Ctesias’ Indica
It was second hand information: Ctesias worked in the Persian court, and relayed fanciful Persian notions of what India was like. Megasthenes, the first Greek author to have actually gone to India and recorded his impressions, was an envoy to India of Seleucus I Nicator, one of the successors of Alexander.