Sudan is a charter member of Intergovernmental Authority on Development (IGAD), established in 1996 as the successor to an earlier regional grouping. The focus of IGAD in the early 2000s was regional cooperation among its seven member states. IGAD played a critical role in ending the war between Khartoum and the Sudan People's Liberation Movement/Sudan People's Liberation Army but otherwise was not effective in mediating regional conflicts because of serious differences among its members, especially Ethiopia and Eritrea. Sudan is a member of the Common Market for Eastern and Southern Africa (COMESA) and is one of 11 COMESA nations that had joined in a free-trade area and agreed to eliminate tariffs on goods originating in member countries. Sudan is a member of the economic union led by Libya known as the Community of Sahel-Saharan States. Sudan also belongs to the African Development Bank (ADB) and receives significant assistance from that organization. As of 2011, it had been in arrears to the ADB since 1995 but had begun making payments in order to pay down the debt. Sudan is an active member of the Nile Basin Initiative, which brought the riparian states together to discuss technical and political cooperation related to Nile water issues.