Column for Earliest date from another table

I have data in 3 tables and related as follows:

I need a column in the right hand table called 'Earliest Req Date' which displays the earliest (min) date of records in the left table, associated with each record in the right table. E.g. if you were to select part number a in the left table, Assy 1,4 and 5 would be associated for which the earliest date is 01/02/19.

Help greatly appreciated.