Final answer:
The question addresses historic trade practices suggested by the use of seals, which authenticated documents or goods, indicating trade between civilizations.
Step-by-step explanation:
The question 'How did these SEALS let us know that they traded?' likely refers to the study of historic trade practices used by early societies or civilizations, which may include examining seals, such as those used in ancient Mesopotamia or the Indus Valley Civilization. Seals were often used to authenticate documents or goods, and the presence of seals found far from their point of origin is evidence of trade. These seals could be found on containers or goods, or impressions might be left on clay tablets and other materials. They let us know about trading practices by showing where goods were sent and received, thus confirming the existence of trade networks.