The kings, who needed the Cossacks in military undertakings and to ward off the inroads of Tartars and Turks, granted them some independence in the Ukraine and Little Russia, and appointed a chieftain over them from their own midst, an Attaman, or Hetman, with special marks of dignity. But the bigoted temper of King Sigismund III and the Jesuits made the Cossacks, who might have become an element of strength for Poland, the source of endless discontent and rebellion. The Zaporogians for the most part were adherents of the Greek Church, the Greek Catholic confession being predominant in southern Poland. After the popes by means of the Jesuits had weakened and oppressed the Polish dissidents, they labored to unite the Greek Catholics with the Romish Church or to extirpate them. With the warlike spirit of the Cossacks this change was not easy; hence a regular system of enslavement was employed against them. Three noble houses, the Koniecpolski, Vishnioviecki, and Potocki, had control of colonization in the Ukraine and Little Russia, and they transferred to their Jewish business agents the farming of the oppressive imposts falling on the Cossacks. Thus Jewish communities gradually spread in the Ukraine, Little Russia, and even beyond these provinces. The Cossacks, for instance, had to pay a tax at the birth of a child and on every marriage. That there might be no evasion, the Jewish revenue farmers had the keys of the Greek churches, and when the clergyman wished to perform a baptism or a marriage, he was obliged to ask them for the key. In general, the position of the Jews in districts where none but Poles dwelt was better than in those which besides Polish inhabitants contained a German population, as was the case in the large cities, Posen, Cracow, Lublin, and Lemberg. By reason of their great number, their importance, and their compact union, the Jews in Poland formed a state within a state. The general synod, which assembled twice a year at Lublin and Jaroslaw, formed a legislative and judicial parliament from which there was no appeal. At first called the Synod of the Three Countries, it became in the first quarter of the seventeenth century the Synod of the Four Countries (Vaad Arba Arazoth). An elective president (Parnes di Arba Arazoth) was at the head, and conducted public affairs. The communities and rabbis had civil, and, to a certain extent, criminal, jurisdiction, at least against informers and traitors. Hence no Jew ventured to bring an accusation against one of his race before the authorities of the country, fearing to expose himself to disgrace and contempt from public opinion, which would have embittered his life, or even entailed death. Almost every community had its college of judges, a rabbi with two assessors, before whom every complaint was brought, but the final decision rested with the synod. The synod also concerned itself about honesty in dealing and conduct, and in weight and measure, wherever Jews were affected.