Vilnius was a prominent city in Lithuania. The language they speak is Lithuanian, which is a very old language. Because it had such a large Jewish population, it was once widely known as the "Jerusalem of Lithuania". Vilnius could even have been considered a world center for Torah study. Rabbi Eliyahu Kremer was a major scholar of Judaism centered in Vilnius, and he was so prominent that he was also known as the "Vilna Gaon". This translates to ‘the genius of Vilna’. His writings have a significant influence among Orthodox Jews to this day. Also, the Vilna Shas is the most widely used edition of the Talmud, and it was published in 1886 in Vilnius.
Before World War II, Lithuania's Jewish community numbered 160,000 people or about 7% of the country's overall population. Vilnius had a Jewish population of about 100,000 people, accounting for around 45% of the city's overall population. Vilnius alone had approximately 110 synagogues and ten yeshivas. Pretty much everywhere in Vilnius was populated by Jewish people.