Thanks for all the suggestions - I'll take a look at the API and see if that helps.
To clarify - the previous site for the client is in Kentico 7 (the new site is Kentico 11). The data I want to migrate consists of a custom page type and all the pages created using that custom page type. I'd rather not recreate these manually as there's a lot of work involved.
Any further suggestions on this could be done?