Migrate Tag History Data Post Migration of Windows/Tags to New Gateway/SQL Server

Long title! :slight_smile:
I may have been a bit short sighted when I migrated some content from one server to another for a customer. In the effort we were tasked with moving a set of OPC tags and windows from one server (that was remote from the site) to a new site based server. My lack of foresight was in regard to the tag history data. So now the customer only has access to data back to when the content was migrated.

What would be the most effective and convenient method to migrate the tag history data from the original server to the new server? Both servers have their own MS SQL server and it would be preferred for the site data to be in the site SQL server.