From “Evreiskaia entsiklopedia” (The Jewish Encyclopedia)  Vol 9, p. 410-411.
Keidany (Caiodunum, Civitas Caiodunensis, in the Samogitian (Žemaičių) language Kwiedajna, in Lithuanian – Kėdainiai). During the period of Polish rule, part of the Samogitian principality. Although Keidany became an important trade center in the reign of Sigismund III, it especially began to develop after being transferred to the Radziwill princely dynasty (1614).
Within the structure of Jewish communal administration, from the 3rd quarter of the 17th century Keidany was the principal town of one of the three counties comprising Medinat Zamut, as the Samogitian area was known. Jews appeared here in 16th century, and in the middle of that century there was already a small Jewish community.
In regulations added to the Magdeburg Law by Janusz Radziwill in 1647, the sixth paragraph states that “executives will be elected by all citizens, regardless of their nationality and religion.” By that time Jews were already significant in the town’s economic life. They were engaged in winemaking, credit operations and also crafts. Jewish craftsmen were organized in special guilds, having the same responsibilities as non-Jewish guilds. Jewish craftsmen, when members of common guilds, were free from dues related to Christian rituals. Conflicts arising between such guilds and Jewish craftsmen who were their members were resolved in the palace court, to which all Keidan Jews were liable in all legal cases and complaints.
Special residential areas were designated for Jews, who were forbidden to purchase or rent houses elsewhere in the town. Jewish creditors could recover debts from debtors’ moveable property, and if that were insufficient, from houses, but only on condition that these be resold to Christians. After becoming citizens of the town, Jews and Christians alike had a year and six weeks to purchase dwellings in the areas designated for them, or they lost the right to trade. Nevertheless, some Jews purchased Christian houses or took them as collateral. This was noted by a committee appointed by Prince Radziwill in 1666 to review the privileges of Keidan citizens.
Among other matters, the committee declared that “Jews must be present at all meetings dealing with taxes, in order to know their obligations and the purpose of such taxes.” Also, “Jews must hold military exercises on a set date each year under the supervision of municipal officials, to determine how many Jews can be called to arms, if needed, to defend the town. Jews must attend these exercises in person and may not send Christians in their place. They are obliged, along with Christians, to participate in the night watch, but may hire workers to substitute for them.”
The following streets, among others, were used as places of residence for Jews: Old Market Street, Pesmilsky [Smilga] Street, Jews’ Street and one side of Crooked Alley. In 1665 the estate of Keidan was leased to one Wolf Isaacovich, who had the authority to judge and punish town residents. To commemorate the persecution of Jews in 1698, Yosef ben Uri from Kobrin composed a penitential prayer.
As a result of wars with Sweden at the beginning of 18th century, the economic situation of the Jews worsened and they sank into debt. One creditor, Gursky, to whom Jews owed several thousand złotys, had all the Jews locked in their synagogue during Shabbat prayers on Saturday, July 30, 1707. In 1766, a census found the Jewish community of Keidan had 501 taxpayers.
Jewish communities in the district continued to hold regional congresses even after the Lithuanian Vaad was cancelled in 1764. It is known that congresses took place in 1778 and 1782. The Rabbi of Brest appeared at the last one to confirm the decisions made there. The position of chief rabbi for Keidan and environs was held by prominent Torah scholars. The pinkas [record book] of the Jewish tailors’ guild of Keidan, including its charter, was preserved by S. M. Dubnov in St. Petersburg.
Keidan is now  part of Kovno province. In the census of 1847, the Keidan Jewish community consisted of 2987 souls. In 1897 there were 6113 inhabitants in Keidan, of whom 3733 were Jews. In 1910 there was one Talmud-Torah.
 Published in 16 volumes between 1908 and 1913 by the Brockhaus and Efron Publishing House, St. Petersburg.
 A congress of Lithuanian Jewish communities, active from 1520 to 1764.
Translated by A. L. Shcherbakov.