The public activity of the Archbishop of Gniezno, Jarosław of Bogoria, coincided with the reign of the last two Piast dynasty on the Polish throne. The culmination of this activity was the reign of Casimir the Great. Quite rightly, Jarosław is considered one of the ruler's closest collaborators and advisors. Archbishop Jarosław of Bogoria enjoyed not only the respect and trust of Casimir the Great. His contacts with Avignon prove that the papacy also saw him as a proven collaborator.