How do historians know that the indus people traded with people from other parts of India?

Historians know that the Indus Valley Civilization engaged in trade with other parts of India due to archaeological evidence, such as the discovery of goods, seals, and weights that indicate a standardized system of trade. Artifacts like pottery, beads, and metals found at Indus sites have been linked to regions like Gujarat and the Deccan, suggesting interregional exchange. Additionally, inscriptions on seals point to a complex trade network that included both local and distant interactions. These findings, combined with historical texts, help confirm the extensive trade relationships of the Indus people.