The African Union recently adopted a Convention for the Protection and Assistance of Displaced Persons, the first legal instrument to define states' obligations toward their own displaced citizens. There are roughly 12 million internally displaced people in Africa. The convention needs to be ratified by a minimum of 15 countries before coming into force. More details here and/or by googling "convention on displaced persons."
You might ask whether conventions like this have any practical effect. The safe, albeit perhaps unsatisfying, answer is that it varies: some have more impact than others. But at a minimum they can help focus attention on a problem, and that in itself can be useful.