How to Bulk-Update Sales Orders in CRM

How to Bulk-Update Sales Orders in CRM

Hi -

I need to bulk update existing sales orders with dates from our ERP of when the sales orders were created.
I made a date field on the Sales Order module where I want to insert that data. I can't Mass Update because I am not updating the fields to the same date, this is a timespan on 3 years and I'm looking to update 1400 records.

Please advise