The Plantagenets were an important family in England that had a big impact on how the country was run during the medieval times. They were in power from the 12th to the 15th centuries and changed many things about society and politics in England.

First, Henry II, the first king from the Plantagenet line, set up a strong central government. This meant that he needed the support of vassals, which were people who got land in exchange for military help. Henry II also introduced "knights." These knights worked for their lords in return for a piece of land called a fief.

Next, two famous kings, Richard the Lionheart and King John, helped strengthen the feudal system. King John’s time as king is well-known for the signing of the Magna Carta in 1215. This important document protected the rights of the nobility. It showed that the king’s power was limited and that he also had to follow the law, creating a balance between the king and his lords.

To sum it up, the Plantagenets not only created the feudal system but also changed the power dynamic between the king and the nobility. This set the stage for how England would be governed for many years to come.