This annual pilgrimage, called the Rosh Hashana kibbutz, drew thousands of Hasidim from all over Ukraine, Belarus, Lithuania and even Poland until 1917, when the Bolshevik Revolution forced it to continue clandestinely. Only a dozen or so Hasidim risked making the annual pilgrimage during the Communist era, as the authorities regularly raided the gathering and often arrested and imprisoned worshippers. Beginning in the mid-1960s, Hasidim who lived outside Russia began to sneak into Uman to pray at Reb Nachman's grave during the year. During "Perestroika" in Soviet Union in 1989, the gates were reopened entirely. In 2008, approximately 25,000 people from all over the world participated in this annual pilgrimage.