Seriously, the creation of South Sudan in defiance of longstanding African determination to avoid opening a Pandora's Box of border-based wars should have been a big deal in showing that redrawing the colonial-era boundaries can solve problems.
But instead of resolving that colonial-era problem, South Sudan remains at war internally:
South Sudan's civil war began on the night of December 15, 2013, when a firefight erupted between soldiers serving in the presidential garrison in the capital city, Juba. "Between" is an important word. The battle pitted soldiers from the Dinka tribe (largest in South Sudan) against soldiers in the Nuer tribe (second largest).
And this complaint about one peace proposal stands out:
The rebels contend [President Salva] Kiir's move violated power sharing agreements central to the ARCISS peace deal. The rebels are right. Kiir imposed a most dangerous gerrymander reminiscent of the worst 19t century European imperialists. Borders of the new states break up tribes, some of which belong to the rebel coalition.
There are always lines to be drawn that will divide people. It just depends on what you are willing to do to enforce--or break--those lines.