Amid their own congratulations and complacency came news of the misfortunes of a neighbouring and rival state; possibly across the border, through Krobatian and Drevlian lands, more probably by a less direct route, by word of merchants from the Oder and Weichsel filtering down from Novgorod or Polotzk, tidings would reach them of wild doings in Poland. Mieceslav II. had “passed in battle and in storm”; and diminished though his territories were under stress of German, Russian, and Bohemian filchings, they were more than a handful for his widow and youthful son to manage. Richense, daughter of Ehrenfrid, Pfalzgraf of the Rhine, tries to play the Queen-mother with the support of a hierarchy itself not yet firmly established; but she is no Olga, moreover she is a German. The bishops are German too, and throne, hierarchy, new religion, and all are involved in the whirlwind of a reaction that scatters them in all directions, Richense to the court of the Emperor in Saxony, her son, Kazimir, to France, where he enters the service of Mother Church as a monk of the celebrated Abbey of Cluny. Yaroslav, taking advantage of the weakness of his western neighbour, began in 1040 a series of campaigns against the tribes which inhabited the dense marsh and river-sected forests lying to the north-east of Poland, between Russia and the Baltic. The Yatvyags first occupied his attention, though it is doubtful if he acquired more than a transient sway over them. He next turned the weight of his arms against the Lit’uanians, upon a section of whom at least he imposed a tribute. The year 1041 found him actually in Polish territory, in the province or palatinate of Mazovia, which had separated from the lands of the Polish crown--if such a designation can be used during an interregnum--under the rule of a heathen noble named Mazlav, from whom the province took its name. Meanwhile the force of the reaction in Poland had spent itself, the bishops retook possession of their dioceses, and Kazimir was fetched, with the Pope’s permission, from the peaceful seclusion of the Burgundian monastery to the management of a country smouldering with the embers of anarchy and religious persecution. Yaroslav seized the opportunity to form an alliance with the young Duke of Poland, by virtue of which the contested Galician or Red Russian March was definitely ceded to the Grand Prince, who on his part helped Kazimir to defeat the rebel Voevoda[20] of Mazovia and reannex that province to his duchy. The good understanding between the princes was cemented by the marriage of Kazimir with Mariya, sister of Yaroslav.