Tribal clashes in eastern Sudan killed at least nine people over the past two days, Sudanese activists said Saturday, in another bout of violence that threatens to derail peace talks in a country marred by decades-long civil wars. Sudan’s transitional government launched negotiations with different rebel groups in October, in neighboring South Sudan’s capital, Juba. The fighting in Port Sudan, in the Red Sea province, grew out of a fist-fight between two people that ended with one stabbed to death, the Sudan Doctors Committee said, leading to his arrest.