One vacation drive we witnessed 100's of dog's being herded across land/field's/roads etc. We could not identify the breed, any idea's?

They were probably English or American Foxhounds. Both are used for hunting in huge packs with the humans following on foot or horseback depending on whether they are hunting or training the pups. English Foxhounds especially are run in extremely large packs and it does look like they are being 'herded'.