Malaria is widespread in the semi-autonomous region of southern Sudan. … Malaria is the number one killer of children in southern Sudan.
I think the meaning of the sentences above could be very slightly different if the bold is Southern Sudan:
- southern Sudan: the south part/region of Sudan
- Southern Sudan: it is a proper noun: a name of nation or country, or region.
Wikipedia says there’s Southern Sudan: Southern Sudan (officially known as the Autonomous Government of Southern Sudan) is located in Africa with Juba as its capital city. Under the terms of the deal with Republic of Sudan, the south has been given a large degree of autonomy and the chance to vote for full independence in 2011 after six years of home rule.
So I think in this case, Southern Sudan is more proper than southern Sudan. What do you think?