50 South Sudanese Pounds

South Sudan's 2011 independence from Sudan made it the world's newest sovereign state at the time, and this note was part of the inaugural currency series issued almost immediately after the July 9 declaration — the South Sudanese Pound replacing the Sudanese Pound at par in the territories that seceded. De La Rue handled the entire first series, a logical choice given their existing relationships across sub-Saharan Africa.

The security specification is notably thin for a denomination of this size — watermark and thread only, with no optically variable ink or other machine-readable elements. That vulnerability became more consequential as the country descended into civil war after December 2013, when currency stability collapsed alongside the political situation.