The Seleucid–Mauryan War was fought between 305 and 303 BCE. It started when Seleucus I Nicator, of the Seleucid Empire, sought to retake the Indian satrapies of the Macedonian Empire which had been occupied by Emperor Chandragupta Maurya, of the Maurya Empire.

The war ended in a settlement resulting in the annexation of the Indus Valley region and part of Afghanistan to the Mauryan Empire, with Chandragupta securing control over the areas that he had sought, and a marriage alliance between the two powers. After the war, the Mauryan Empire emerged as the dominant power of the Indian subcontinent, and the Seleucid Empire turned its attention toward defeating its rivals in the west.