Union Berlin were promoted to the Bundesliga for the first time in their history on Monday after beating Stuttgart in a promotion-relegation play-off.

Having narrowly missed out on the top-tier in 2017, they are the first club from the former communist East Germany to reach the Bundesliga since Energie Cottbus were relegated in 2009.

Union and Stuttgart drew 0-0 on Monday having also drawn 2-2 in the first-leg on Thursday and went through on away goals.

While Bundesliga high-flyers RB Leipzig, who came up in 2016/17, are also from the East, they were founded in 2009 -- long after German reunification.

Union, by contrast, are an icon of the communist era, and spent the 1970s and 1980s yo-yoing between the top two divisions of East German football.

Their Alte Foersterei stadium, nestled in the forests of East Berlin, earned a reputation as a lightning rod for those critical of the regime.

Since the fall of the Berlin Wall, Union have established themselves as a rare success story of East German football.

Like many former East German clubs, they initially struggled with severe financial difficulties in the wake of reunification, but have since become one of the healthiest clubs in the region.

Having earned promotion from the third tier in 2009, they have remained in the second division ever since, a rare bastion of stability in a volatile league.

In recent years, Union have developed cult status due to their passionate support. Their fans famously helped to build the current stadium during a 2008 renovation, and gave blood to help the club pay off its debts in 2004.

Promotion to the Bundesliga ranks among the clubs greatest on-field achievements, alongside their East German Cup triumph of 1968, and a German Cup final appearance in 2001.

In Union and their West Berlin rivals Hertha, the German capital will be able to boast of two Bundesliga clubs this season.

It will be the first time that two clubs from a single city have been in the top flight since 2010/11, when Hamburg were joined by cross-city rivals St. Pauli.

Joining Union will be second-tier champions Cologne as well as Paderborn and heading down with Stuttgart are former Germany champions Hannover and Nuremberg.