In the 16th century, Lithuania and Poland formed a commonwealth, with a joint sovereign and parliament, but separate administrations. Following the third partition of the Polish-Lithuanian Commonwealth in 1795, the commonwealth lost lands in the west to Prussia and in the east to Russia. What remained became the Kingdom of Poland. During World War I, Lithuanian lands came under German occupation. After the armistice of 1918, the Soviet army occupied Lithuanian lands. By 1921, Lithuania had become an independent nation, with Vilna and other areas claimed by both Lithuania and Poland and under constant dispute. In World War II, Lithuania was first occupied by the Soviet Union, and then, in 1941, by Germany. By 1944 most of Lithuania had been reoccupied by the Soviet Union. Lithuania remained under the Soviet sphere until 1991, when it became an independent nation.
Once you have identified the name of your ancestral town, you can locate it on a map using the following sources. It is also very helpful to identify the district and province in which the town was located at the time your relatives lived there, as well as the current district and province, using historical atlases and/or the web site listed below.
Dov Levin. The Litvaks: A Short History of the Jews in Lithuania (Jerusalem: Yad Vashem, 2000). This book includes an appendix of Jewish communities and localities in inter-war Lithuania, listing the Lithuanian and Yiddish town names. Reading Room DS 135 .E81 L5813 2000
Mokotoff, Gary, Sallyann Amdur Sack, and Alexander Sharon. Where Once We Walked—Revised Edition: A Guide to the Jewish Communities Destroyed in the Holocaust (Bergenfield, NJ: Avotaynu, 2002). This gazetteer lists towns according to variant spellings and provides the map coordinates of the towns, as well as an estimate of the pre-WWII Jewish populations. Genealogy Institute DS 135 .E83 M65 2002