These are assumed to represent the rulers of the provinces. Heads turned upside down are believed to represent the rulers killed and whose provinces were taken by force, while the upright ones may represent those who did not resist annexation and had their lives spared.
The figures depicted on these objects are thought to be a symbolic representation of the rulers of the provinces.  Heads turned upside down suggest rulers killed during annexation, while upright heads indicate those who surrendered peacefully and survived.