Jahn, as the club tends to be colloquially called, is, like most German clubs, a result of several mergers and splits over the last century and more. 

The very first forerunner club was a multi-sport club founded in 1886. The football division of that club broke away in 1924 and then merged ten years later with another sports club (founded in 1899) and a swimming club to form SSV Jahn 1889 Regensburg (hence the date 1899 seen in many places in association the club). 

The football division separated from the parent club in 2000 to become the independent SSV Jahn 2000 Regensburg. 

Nine years later, in 2009, the professional footballing side was spun off into a limited company, at which point the club renamed itself to SSV Jahn Regensburg, with the limited company bearing the snappy name SSV Jahn Regensburg GmbH & Co. KGaA. At the time of writing, the club (which has c. 5,000 members) holds 90% of the shares in the limited company, while investors hold the other 10%.

The club has spent most of its history playing in the lower leagues of German/Bavarian football. As recently as 1999, it was playing in the fifth tier. Since then, however, it has generally played in the third tier 3. Liga (of which it was a founding member in 2008) or the 2. Bundesliga.

Having played on the same site from 1926 to 2015, the club moved into a new out-of-town stadium, the Jahnstadion Regensburg at the start of the 2015/16 season. I've written more about that on the 'Stadium' page.

Rival clubs in the region are SpVgg Unterhaching,FC Ingolstadt 04 and Wacker Burghausen. While the media apparently like to hype up games against Ingolstadt as the 'Danube derby', many Jahn fans regard Ingolstadt as an artificial club (due to its funding from Audi) and thus don't place the same importance on those matches. For them the keener rivalry is with Burghausen and the competition to be the top club in East Bavaria.