Very broadly, the data comes from your Salesforce data that syncs to Deals.

More specifically, AI Forecast uses the Opportunity, Opportunity History and Account Salesforce objects. 

In addition, AI Forecast leverages the New Business settings configuration, the Amount field configuration, and the configurations for team quarters.

To train the model, opportunities that satisfy the following are used: 

• New business deal settings (from our Deals Admin settings) 
• Closed opportunities
• Opportunities that have create and close dates falling within certain date ranges.