From that time on, Jewish lease holders were active only in Red Ruthenia, Podolya, Volhynia, west bank Ukraine and Lithuania. In the tenancies supervised by the Jews as well as in the estates run by the gentry, feudal exploitation of the peasant serfs often led to local revolts which in the Ukraine turned into a Cossack and peasant uprising. The cooperation of the Jewish lease holders with the magnates in the latter's colonial policy caused these revolts often to be held under the slogan of struggle against the Poles and Jews. Next to crafts, trade, banking and leasing operations, agriculture had become an increasingly important source of income for the Jewish population in the eastern regions of the Commonwealth. Maciej Miedhowita, author of the Polish Chronicle (1519), when mentioning Jews, says that in Ruthenia they were engaged not only in moneylending and trade but also soil cultivation. In towns Jews owned fields and gardens. In Chelm in 1636 Jewish landless peasants were forced to do serf labor. In villages Jews also toiled the land adjoining the inns, mills and breweries they held in lease. Some Jews earned their living as paid kahal officials, musicians, horse drivers, factors on gentry estates and in the houses of rich merchants, as middlemen known as barishniki, servants, salesmen, etc. There was also a large group of beggars and cripples without any means of subsistence. Only some of them obtained from time to time assistance from charity organizations and were given a place to sleep in an almshouse.
In view of the growing financial differentiation among the Jews social conflicts intensified. The middle of the 16th century saw the beginning of opposition by Jewish craftsmen against individuals who placed their capital in leather, textile and clothing manufacture. The struggle of the populace against rich merchants and bankers was reflected in the activity of Salomon Efraim of Keczyca, an outstanding plebeian preacher. In his book Ir Gibborim (The Town of Heroa), published in 1580 in Basle, he sharply criticized the exploitation of the poor by the rich. He also attacked the rabbis who tried to gain the favor of the wealthy Jews. He presented his views not only in his books and lectures in the synagogue, but also during fairs which were attended by numerous Jews. There are records of joint revolts by Jewish craftsmen and Christian "patcher" against the guild elders. There were also joint revolts of the Jews and the burghers against the gentry. This found expression in an agreement which in 1589 Jews in Kamionka Strumilowa concluded with the municipal authorities "with the consent of all the populace". The councilors "accepted the Jews into their own laws and freedoms while they [the Jews] undertook to carry the same burdens as the burghers". Jews pledged themselves to help in keeping order and cleanliness in the town, hold guard and take part in anti-flood operations together with Christians. The latter promised that they would "defend those Jews as our real neighbors from intrusions and violence of both the gentry and soldiers. They would defend them and prevent all harm done to them... since they are our neighbors."
The rapid development of Jewish settlement and economic activity was accompanied by expansion of their self-government organization. In the 16th century its structure had no equal in all of Europe. As in the Middle Ages, every autonomous Jewish community was governed by its kahal or a collegiate body composed of elders elected as a rule from among the local wealthiest The kahal organized funerals and administered cemeteries, schools, baths, slaughterhouses and the sale of kosher meat. In the closed "Jewish cities" it also took care of cleanliness and order in the Jewish quarter and the security of its inhabitants. To this should be added the administering of charities such as the organization of hospitals and other welfare institutions and the dowering of poor brides. Another important function was to establish the amount of taxes each individual household in the given community was to pay. The further hierarchic development of the Jewish autonomous institutions was connected with the difficulties which in the early 16th century the authorities encountered in exacting taxes.
Between 1518 and 1522 Sigismund Augustus decreed the foundation of four Jewish regions called lands. Each of these lands was to elect at a special diet its elders, tax assessors and tax collectors. In 1530 the king established a permanent arbitration tribunal based in Lublin which was to examine disputes between Jews from various lands. In 1579 Stephen Bathory called into being a central representation of Jews from Poland and Lithuania with responsibility for exacting poll taxes which had been introduced for the Jewish population in 1549. This institution, known as the Diet of the Four Lands (Va 'ad Arba Arazot), was constituted at a congress in Lublin in 1581. The Diet of the Four Lands, which usually was summoned once a year, elected from among its number a council, known as the Jewish Generality. The latter was headed by a Marshal General and included a Rabbi General, Scribe General and Treasurers General. The diets were attended by representatives of both Poland and Lithuania until 1623 when, following the establishment of a separate taxation tribunal for Lithuanian Jews, a separate diet of Lithuanian Jews was also set up. These institutions continued in existence until 1764. The diet of Polish Jews usually convened in Lublin, sometimes in Jaroslaw or Tyszowce, while the Lithuanian diets debated most often in Brest Litovsk.
The diet or Va 'ad represented all the Jews. It carried out negotiations with central and local authorities through its liaison officers (shtadlans) who, by their contacts with deputies, tried to influence the decisions concerning Jews taken by the Sejm and local diets of the gentry. During the sessions of the ra 'ads not only fiscal matters were discussed but also those related to the well-being and cultural life of the Jewish population in the Commonwealth. They took decisions on the lease of state products, the amount of interests in credit transactions among Jews, the protection of creditors against dishonest bankrupts, the upbringing of young people, the protection of the family, etc. The Va 'ad also took decisions on the taxation of the Jewish population, for example for defensive needs of the country. The main tax was the poll tax. In addition the Jews, like the rest of the burghers, paid taxes for the city's defenses. Besides taxes, all townsfolk, irrespective of religion, were obliged to perform certain tasks and contribute money in order to build and expand defensive systems and maintain permanent crews of guards.
The Jews, like the Christian population, had personally to contribute to the town's defense preparedness. In the Jewish quarter the most important structure was the fortified synagogue. In the 16th and 17th centuries several dozen such buildings were erected in Poland's eastern borderlands, including such places as Brody, Buczacz, Czortkow, Husiatyri, Jaroslaw, Leszniow, Lublin, Luck, Podkamien, Pomorzany, Sokal, Stryj, Szarogrod, Szczebrzeszyn, Szydlow, Tarnopol, Zamosc and Zolkiew. One of the main duties of all townsfolk, including the Jews, was to defend the city as a fortified point of resistance in case enemy troops succeeded in forcing their way through into the country. In the early 16th century in the Grand Duchy of Lithuania to this was added the duty of providing a contingent of soldiers. After 1571 this duty was changed to appropriate money dues. For the first time Jews were ordered to provide an army contingent in 1514 but this obligation began to be exacted more consistently only after 1648. As was the case with the remaining population Jews acquired their military training during obligatory exercises and their fighting preparedness and ability to wield arms were tested during special parade.
The first mention of a Jew's direct participation in battle against enemies of the Commonwealth dates from the middle of the16th century. During the reign of Stephen Bathory there served in the Polish army one Mendel Izakowicz from Kazimierz near Krakow. He was a bridge builder and military engineer and during the war against Muscovy rendered considerable services to the Polish army. During the war with Muscovy in 1610-12 in one regiment only, probably one of those belonging to Lisowski's light cavalry, more than ten Jews served at one time. A certain number of Jews also fought on the Polish side in the Smolensk war of 1632-34 and some of them were taken prisoner by the enemy. The year 1648, when the Cossack uprising under Bohdan Chmielnicki broke up, was a breakthrough in the history of both the Commonwealth and Polish Jewry. The country was plunged into economic crisis made worse by war devastation. The wars against the Ukraine, Russia, Sweden, Turkey and the Tartars, which Poland fought almost uninterruptedly between 1648 and 1717, brought in their wake a permanent downfall of towns and agriculture and decimated the population.
During Bohdan Chmielnicki's revolt and wars against the Ukraine and Russia Jewish communities in the areas occupied by enemy troops were completely wiped out. Some Jews were murdered, some emigrated to central Poland and the rest left for Western Europe. The drop in the number of the Jewish population during the Ukrainian uprisings (1648-54) is estimated as amounting to some 20 to 25 per cent, that is between 100,000 and 125,000. A rapid growth in the number of the Jewish population was recorded only in the 18th century, after 1717. It is estimated that in 1766, when the census of Jews obliged to pay poll taxes was concluded, there were in the Commonwealth as a whole some 750,000 Jews, which constituted seven per cent of the total population of Poland and the Grand Duchy of Lithuania. According to Rafal Mahler, at this time some 29 per cent of all Jews lived in ethnically Polish areas, 44 per cent in Lithuania and Byelorussia and 27 per cent in regions with a predominantly Ukrainian population. Two thirds of all Jews lived in towns and the remainder in the countryside.
Following the first partition of Poland some 150,000 Jews found themselves under Austrian occupation, about 25,000 in the Russian zone and only 5,000 in Prussia. The population census conducted in Poland in 1790-91 demonstrated a further increase in the number of Jewish inhabitants. Tadeusz Czacki estimated them at over 900,000, that is some 10 per cent of the total population of the then Commonwealth. In the same period (1780) in the Austrian zone there were over 150,000 Jews and several tens of thousands in the remaining partition zones. The reconstruction of towns after each war took a long time. The quickest to emerge from ruin were the estates of magnates who willingly employed the Jewish population. In the eastern part of the Commonwealth and partly in central Poland Jews played an important role in reactivating crafts, and not only such traditionally Jewish branches as goldsmithery, pewter, haberdashery and glass manufacture, furriery and tailoring, but also tin and copper working, arms production, carpentry, printing, dying and soap manufacture. There appeared in this period a large number of Jewish craftsmen who traveled from village to village, from manor to manor, in search of temporary employment. The material situation of Jewish craftsmen was generally difficult.
The pauperization of towns and villages made it hard to sell their products both for Jewish craftsmen and their Christian counterparts. In the large cities, rivalry between the guilds on the one hand and the Jewish and Christian "patchers" on the other bred conflicts. These often ended in compromise and Jews more often than ever before were admitted to Christian guilds. At the same time, next to the old ones, new, purely Jewish guilds were formed, for example in Poznari, Krakow, Lvov, Przemysl, Kepno, Leszno, Luck, Berdyczow, Minsk, Tykocin and Bialystok. During the wars of the middle of the 17th century Jewish wholesale trade, both long distance and foreign, came nearly to a standstill. Only in some cities, for example Brody and Leszno, Jewish merchants, thanks to considerable support on the part of the magnates, succeeded in renewing contacts with Gdansk, Wroclaw, Krolewiec, Frankfurt on Oder and to a lesser degree with England. Thanks to the magnates' assistance local Jewish trade also began to expand. Most shops in the reconstructed town halls were leased to Jews (for example in Staszow, Siemiatycze, Kock, Siedlce and Bialystok). Peddling was also spreading as a result of which trade exchange between town and country, interrupted during the wars, was revived.
After the middle of the 17th century wars radical changes took place in the organization of credits. Large banking houses disappeared and the kahals, instead of being creditors, turned into debtors. Representatives of the gentry and the clergy increasingly often placed their money in Jewish communities at the same time forcing the latter to take genuine responsibility for the debts of individual Jews. In case a kahal was unable to repay its debts, the gentry had the right to seal and dose down its prayer house, imprison the elders and confiscate goods belonging to merchants. In order to safeguard themselves against the lightheartedness of individual debtors the communities applied the credit hazakah, which consisted in the community issuing permissions to its members who wanted to avail themselves of credit. Whether someone was given a loan or not was often decided by a clique consisting of the kahal elders. Part of the capital leased from the gentry and the clergy and augmented by means of interest disappeared into the pockets of the kahal oligarchy, while part of it was turned over to nonproductive purposes, for example to financing defense in ritual murder trials, paying for the lords' protection, etc.
In the first half of the 18th century the gentry and the clergy became anxious of the fate of money located in the Jewish communities and the interests from unpaid debts which were growing in a landslide. When the above mentioned methods failed to produce adequate results, the krupki were applied, that is a consumption taxation, the income from which was destined totally for paying off the debts. Finally in 1764 a decision was taken on abolishing kahal banks altogether and servicing debts by taxing each Jew. As a result of the general impoverishment of the Jewish population in the second half of the 17th and in the 18th century, differences between the people and the kahal oligarchy deepened, the latter trying to pass the burden of the growing state and kahal taxes onto the shoulders of the poorer classes. In several cities, for example in Krakow, Leszno and Drohobycz, the Jewish poor revolted against the kahal oligarchies. A fierce struggle against the kahals was carried out by Jewish guilds which tried to free themselves from their economic dependence.