Border clashes and rows about oil wealth cloud the relationship between South Sudan and Sudan eight months after the south seceded, with some fearing a new outbreak of open warfare.
One man with a rare insight into the two countries is photographer Tim McKulka. He spent five years travelling to every state in the united Sudan - then Africa's biggest country - to produce a book We'll Make Our Homes Here: Sudan at the Referendum, which will soon be available for free on iTunes.
He explains why he decided to undertake such an ambitious project.
Photography by Tim McKulka, interview by James Copnall.Slideshow production by Emma Lynch. Publication date 13 March 2012.
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