Importing Tasks and tie them to contacts

Importing Tasks and tie them to contacts

I can't tie tasks to contact or accounts (whereas I have a field contact and an account field in my task.csv file).

Rishi (from Zoho CRM) wrote this on this forum :
"More over its not possible to associate the activities to a contact or any other record by importing a file into Zoho CRM. Normally when you do a complete migration then the records get associated if you have the record ids in the CSV files. "

Could you please give me further details ? How the task_id will be linked to contact (because contact doesn't have an ID)?