One Combobox changing another's rowsource

Hi there, I'm new to VBA and am looking for some assistance!

I have created a userform that has 2 comboboxes, Region, City / County. I would like the comboboxes to pull data from the same sheet.

I have set a static cell range in the rowsource area of the properties box of the Region combobox.

What I would like to happen on the userform is the options available in the drop down menu of the City / County to be determined by the selection made previously in the Region combobox. So I need to use code so that the rowsource of the City / County combobox reacts dynamically to the selection made in the Region combobox.

I have data inputted on columns C - G for the Region combobox to pull from.

Hopefully somebody can help, I've attached a sample workbook, so would appreciate any assistance.

Thanks in advance.

John