A System Integration Testing (SIT) environment is used as an environment to perform system-to-system testing. This means that the SIT environment is used to test the integration of different systems or components that are part of the Salesforce Manufacturing Cloud solution. The SIT environment allows the verification of the functionality, performance, and reliability of the integrated systems, as well as the identification and resolution of any defects or issues that may arise during the integration process. The SIT environment is typically a replica of the production environment, but with a smaller data set and lower security requirements. The SIT environment is also used to validate the data migration and synchronization between the source and target systems, as well as the compatibility and interoperability of the APIs and web services that are used for the integration.Reference:

Manufacturing Cloud - Salesforce

How to Perform Automated Integration Testing in Salesforce

Automate and Test During Integration