What is the theme in Nibelungenlied ?

Chivalry was a code of behavior which evolved in the Middle Ages. It is associated with the tradition of mounted knights in armor, lord and ladies, feasts, jousts, and war games. In fact, "knights" arose from the development of new military techniques. The behavior of a knight both on the battlefield and in everyday life was expected to follow a certain set of rules— a moral, social and religious code of conduct. The notion of chivalry encouraged knights to foster the virtues of courage, honor, and service to their lord or kinsmen.