Looks like a blackberry (Rubus sp.) thicket. Not sure about eradication technique other than herbicide since it spreads by suckers from the roots and would come back up from any stray roots left in the ground. If left unchecked, blackberries can get away from you!
hortster

Digging is the most effective. Then check during successive years to get the seedling & re-sprouts from missed roots.

Looks like Himalayan Blackberry, Rubus armeniacus. Extremely invasive in many states. Your local(county/state)noxious weed control board can give you info on how to best control it in your area(mechanical methods, spray schedules, etc).

Keep in mind that spraying herbicides, plant poisons, is harmful to our environment and has been shown to cause genetic mutations in lower order creatures that may indicate problems for us. What is the reason for the genetic changes in us humans since these products have seen greater use since the 1950's?