Ukrainian Jewry has endured both times of discrimination as well as times of development and success. The Jews have been living in Ukraine since before the Common Era, where they worked with Greek traders near the Black Sea. Their population really expanded in the 13th century through migration of Jews from the Rhineland in particular. A large number of Jews during this period worked as artisans and merchants, but the largest amount of income came from the arenda system. The Jews were put in charge of the arendas and given the power to collects taxes while also the power to make and sell alcohol. This system allowed the Jews to become successful and helped their population to increase. By the end of the 19th century the Jews, compared to the Ukrainians, were more concentrated in urban settings.