Around the end of the 11th century and the middle of the 13th century. It ended because people considered the knights to be violent and the feudal system was outdated. The fact that knights protected their lord in order to gain food and a place to stay just wasn't needed, and took up to much money.
"The end of feudal society meant that sovereigns gained a monopoly on war-making, and the old form of military service owed to one's immediate lord became obsolete"
