Because South Sudan is it must ship its oil through pipelines and ports in Sudan

Because South Sudan's Dar blend trades at a significant discount to Brent, a drop in ... and must be heated during transport to avoid congealing in ship tanks. ... South Sudan exports all of its crude oil via pipeline through Sudan. ... The other full-conversion refinery is the Port Sudan refinery (21,700 b/d),

Explanation:

worcester v. georgia, legal case in which the u.s. supreme court on march 3, 1832, held (5–1) that the states did not have the right to impose regulations on native american land. andrew jackson refused to enforce the ruling, the decision form the basis for most subsequent indian law in the united states.