the polish piast dynasty under mieszko i had extended their domains beyond the oder river, where their claims to power collided with the interests of the saxon margrave gero. after his defeat by gero's troops in 963, mieszko i decided to come to terms with emperor otto i and agreed to pay tribute for this part of his lands. in turn he gained the title of "amicus imperatoris" ("friend of the emperor") and the acknowledgment of his position as a "dux" of poland. he continued his policy of convergence with the empire by marrying oda, the daughter of the saxon margrave dietrich of haldensleben, in 978 and by marrying his son bolesław i to a daughter of margrave rikdag of meissen. as a precaution however, shortly before his death in 992 he placed his realm (civitas schinesghe) under the protection of pope john xv according to the "dagome iudex" regest.