Sudan mess has been a genocide 20 years in the making. The blacks have had little or no help as the Arab north has killed, raped and stole their land. The reason nobody has helped is that their is no major money involved. Millions of innocents have died, while the world sat around doing nothing simple because the area was not rich in minerals, oil, etc.
The Congo is a seas of instability with multiple "as many as 20" tribal -political groups looking for power over it's rich resources. This nation has never known any degree of freedom from murderous groups seeking power.None of this wealth has ever gone to the people who have been subject to mass murdering and raping.