Filter dropdown items based on selection of the previous Items

I would like to create dropdown items, but in this case i want to be selecting items of the drop down based on the previous selection

For example;
I have Regions, SubRegions, County, subcounty etc up to village level
So what i want is to filter only subregions of a particular region and also counties of a selected sub region.

I stand to be corrected if i have not explained it well.