In 1815 the German Confederation was formed. It was an association of 39 different states. Each state had its own system of measurements. In 1834 the German Confederation formed a customs union called the "Zollverein". In 1851 the "Zollverein" decided to use metric units for trade between the various states. In 1871, most of the states in the German Confederation were joined together to form the German Empire. The German Empire continued to use the metric system.