Trephination

Trephination.

The hole in this skull was purposely created using a process termed "trephination."
This technique was used in many ancient cultures to allow for the exiting of "evil spirits." It may also have been successful in treating/evacuating a subdural hematoma. Meningitis is a concern when performed in such unsterile conditions though.

The location is on the right parietal bone, near the function of the frontal bone. Note that the hole likely does not cross the midline. These cultures must have discovered the sagittal venous sinus runs in the midline and damage could result in death.