The Steuerverein (Tax Union) was formed in 1834 as a customs union first of the Duchy of Brunswick and the Kingdom of Hanover and then with the Grand Duchy of Oldenburg in 1836. Hanover joined the Deutscher Zollverein (German Customs Union) in 1854, after negotiating advantageous conditions with Prussia. Facing isolation, Oldenburg followed suit in 1854, thus ending the Steuerverein. Beginnings Moves to a north German customs alliance occurred in 1830, when Hanover, the Electorate of Hesse, the Grand Duchy of Oldenburg and Brunswick concluded the Einbeck Treaty as a supplement to the Central German Commercial Union. This provided for tariff free trade between the contracting parties and a common customs administration and external tariff. Excluded from the regulation were the trade in salt (a state monopoly). Since the contracting parties could not reach an agreement on the amount of the external customs duties, the contract did not come into force. In addition, Electoral Hesse joined the Prussian-Hessian Customs Union instead. A new attempt to forge a north German customs union was made and an agreement between Hanover and Brunswick came into force on 1 June 1835. The two states agreed a customs union with internal tariff free trade, a common external tariff and a common customs administration. The customs revenue was divided according to their respective populations. The external tariffs on materials imported from overseas and on finished goods were below the rates of the Deutscher Zollverein. Like the previous agreement, salt was excluded from internal tariff free trade. Relations with Zollverein The Steuerverein did not arise from hostility to the Prussian customs unions, but rather from the requirements of a population upon which the higher duties of the Zollverein external tariff would have been injurious because of import duties on articles of consumption, especially colonial produce, of which Hanover was a large importer. In 1837 a Convention between the Zollverein and Steuerverein was signed which greatly reduced Zollverein import duties on imports from the Steuerverein States, such as corn, hops, butter, leather, iron, glass, and earthenware; duties on linen and linen-yarn were entirely removed. In return, the Steuerverein took measures to suppress smuggling into the Zollverein, including adjustments of outlying territory to provide a more easily policed customs cordon. Parts of the Steuerverein member states did not belong to the Steuerverein territory. Provinces of Oldenburg situated in other parts of Germany, namely the Duchy of Birkenfeld and the