All of these are examples of "Special-Purpose Governments". These are levels of government that are created to handle a single task.
1.An astrolabe was an instrument which helped sailors to find their location by looking at the stars and sun
2. Crusaders were people who went on the Crusades
3. The feudal system was the social, economic, and political system of Europe in the Middle Ages
4. A manor was a large estate or farm, part of which was set aside for the lord and the rest divided among his peasants
5. The Middle Ages was the period in European history between ancient and modern times, from about A.D. 500 to about 1500
6. A Muslim is a believer in the religion of Islam; a follower of Mohammed
7. A serf was a peasant in the feudal system midway between a freeman and a slave
