Megasthenes was a Greek historian, diplomat, and ethnographer of the early Hellenistic period, active in the late 4th and early 3rd centuries BCE. He served as an ambassador for Seleucus I, a successor to Alexander the Great, to the court of the Indian emperor Chandragupta Maurya. His exact origins are uncertain, but he likely came from Ionia in Asia Minor. His diplomatic role gave him unique access to the Mauryan Empire, and he spent time at the imperial capital, Pataliputra, and traveled within India.

His major work was the Indica, a multi-volume account of India. The original text is lost but survives in fragments quoted by later Greek and Roman historians. It described India's geography, peoples, customs, government, and natural history based on his observations.

Megasthenes' work became the foundational Greek source on India for centuries, shaping the classical world's knowledge of the subcontinent. According to modern scholars, his reports on the sophisticated Mauryan administration provide valuable external testimony about early Indian statecraft. He also described Indian social structures and ascetic philosophers, sparking Greek philosophical interest. While his accounts sometimes included marvels and inaccuracies, his direct access makes the Indica a critical historical source. His identification of the Indian king "Sandrokottos" with Chandragupta Maurya was particularly important for aligning Greek and Indian historical timelines.