Jewish settlers founded the Ashkenazi Jewish community in the Early (5th to 10th centuries CE) and High Middle Ages (circa 1000–1299 CE). The community survived under Charlemagne, but suffered during the Crusades. Accusations of well poisoning during the Black Death (1346–53) led to mass slaughter of German Jews, and they fled in large numbers to Poland. The Jewish communities of the cities of Mainz, Speyer, and Worms became the center of Jewish life during Medieval times. "This was a golden age as area bishops protected the Jews resulting in increased trade and prosperity." The First Crusade began an era of persecution of Jews in Germany. Entire communities, like those of Trier, Worms, Mainz, and Cologne, were murdered. The war upon the Hussite heretics became the signal for renewed persecution of Jews. The end of the 15th century was a period of religious hatred that ascribed to Jews all possible evils. The atrocities during the Khmelnytsky Uprising committed by Khmelnytskyi's Cossacks (1648, in the Ukrainian part of southeastern Poland) drove the Polish Jews back into western Germany. With Napoleon's fall in 1815, growing nationalism resulted in increasing repression. From August to October 1819, pogroms that came to be known as the Hep-Hep riots took place throughout Germany. During this time, many German states stripped Jews of their civil rights. As a result, many German Jews began to emigrate.
From the time of Moses Mendelssohn until the 20th century, the community gradually achieved emancipation, and then prospered. In January 1933, some 522,000 Jews lived in Germany. However, following the growth of Nazism and its antisemitic ideology and policies, the Jewish community was severely persecuted. Over half (about 304,000) emigrated during the first six years of the Nazi dictatorship. In 1933, persecution of the Jews became an active Nazi policy. In 1935 and 1936, the pace of persecution of the Jews increased. In 1936, Jews were banned from all professional jobs, effectively preventing them from participating in education, politics, higher education, and industry. The SS ordered the Night of Broken Glass (Kristallnacht) to be carried out the night of November 9–10, 1938. The storefronts of Jewish shops and offices were smashed and vandalized, and many synagogues were destroyed by fire. Increasing antisemitism prompted a wave of a Jewish mass emigration from Germany throughout the 1930s. Only roughly 214,000 Jews were left in Germany proper (1937 borders) on the eve of World War II.
Beginning in late 1941, the remaining community was subjected to systematic deportations to ghettos, and ultimately, to death camps in Eastern Europe. In May 1943, Germany was declared judenrein (clean of Jews; also judenfrei: free of Jews). By the end of the war, an estimated 160,000 to 180,000 German Jews had been killed under the Nazi regime, by the Germans and their collaborators. A total of about 6 million European Jews were murdered under the direction of the Nazis, in the genocide that later came to be known as the Holocaust.
After the war, the Jewish community in Germany started to slowly grow again. Beginning around 1990, a spurt of growth was fueled by immigration from the former Soviet Union, so that at the turn of the 21st century, Germany had the only growing Jewish community in Europe, and the majority of German Jews were Russian-speaking. By 2014, the Jewish population of Germany had leveled off at 118,000, not including non-Jewish members of households; the total estimated 'enlarged' population of Jews living in Germany, including non-Jewish household members, is close to 250,000. 
Currently in Germany, denial of the Holocaust or that six million Jews were murdered in the Holocaust (§ 130 StGB) is a criminal act; violations can be punished with up to five years of prison. In 2006, on the occasion of the World Cup held in Germany, the then Interior Minister of Germany, Wolfgang Schäuble, urged vigilism against far-right extremism, saying: "We will not tolerate any form of extremism, xenophobia, or anti-Semitism." In spite of Germany's measures against these groups and anti-Semites, a number of incidents have occurred in recent years.
Jewish migration from Roman Italy is considered the most likely source of the first Jews on German territory. While the date of the first settlement of Jews in the regions which the Romans called Germania Superior, Germania Inferior, and Magna Germania is not known, the first authentic document relating to a large and well-organized Jewish community in these regions dates from 321 and refers to Cologne on the Rhine (Jewish immigrants began settling in Rome itself as early as 139 BC). It indicates that the legal status of the Jews there was the same as elsewhere in the Roman Empire. They enjoyed some civil liberties, but were restricted regarding the dissemination of their culture, the keeping of non-Jewish slaves, and the holding of office under the government.
Jews were otherwise free to follow any occupation open to indigenous Germans and were engaged in agriculture, trade, industry, and gradually money-lending. These conditions at first continued in the subsequently established Germanic kingdoms under the Burgundians and Franks, for ecclesiasticism took root slowly. The Merovingian rulers who succeeded to the Burgundian empire were devoid of fanaticism and gave scant support to the efforts of the Church to restrict the civic and social status of the Jews.