Stumped on update query between tables with no Join fields

I have two tables related to sales transactions and assigned areas.

The tblSalesArea has SalesAreaID an autonumber
                        StartZip, Text
                        EndZip, Text

The tblSales has many fields detailing all the sales.  The two fields of 
concern are
ZipCode, Text and SalesAreaID a number.

I need to populate the tblSales!SalesAreaID with the 
tbleSalesArea!SalesAreaID
based on the zipcode being between tblSalesArea!startzip and 
tblSalesArea!endzip.

This is where I am and it doesn't work.  I suspect because the tables are 
not joined.
I could open two datasets and do it pretty easily in code but that would
be 
slow.
Any Ideas??

Thx

UPDATE tblCentral, tblSalesAreas SET tblCentral.OwnerID = 
tblSalesAreas!CompanyID
WHERE (((tblCentral.SoldToZip)>=[tblSalesAreas]![StartZip] And 
(tblCentral.SoldToZip)
<=[tblSalesAreas]![EndZip]));