JUBA, Sudan — On the desk in his office in Juba, the capital of what will soon be the world’s newest country, R. Barrie Walkley, the American consul general, has a telling picture. It is of him and George Clooney shaking hands in a crowd during the independence referendum here in southern Sudan in January.

The photograph offers a unique window into what is happening now. American celebrities and religious groups teamed up with policy makers and helped a forlorn underdog region finally achieve what very few separatist movements achieve: independence. On Saturday, after decades of guerrilla struggles and intense international pressure, the Republic of South Sudan will officially split off from the north and become Africa’s 54th country.

“Once you got someone like George Clooney, for example....” Mr. Walkley trails off with a smile. “George packs power.”

Sudan has been an obsession for the West for more than 100 years, and it is an interesting question why, of all the world’s war zones and all the blood baths Africa has witnessed — Liberia, Somalia, the Democratic Republic of Congo, to name a few — this place has grabbed so much attention.