The head of the government was the king. In each of the governed districts, there was a governor who was the head of a complex bureaucracy. Each district paid tribute to the king and provided troops. Every time an area was conquered, most of the population was dispersed throughout the other districts, and colonists from the rest of the empire were placed into that new district. This principle of dispersed slavery caused quite a stink in the ancient world, and eventually led to the fall of the Assyrian Empire.