Abstract: This article is about the history of the Treaties. It mentions the doctrinal conceptualization and definitions of the theme. It deals with the formal evolution of the subject relating to the citizens, the content, the procedure and the effect.

The author speaks of the principles of international relations that are characteristic of each phase: the principles of the unit, the balance and the International Organizations, which are related to the Middle, Modern and Contemporary Ages, respectively.

Keywords: Treaties; Evolution; Definitions; Principles.