. Identification re ention and reduction o state essness UNHCR, at least 620,000 people worldwide remain stateless as a result of State succession within the last 30 years.89 State succession occurs where there is: — a transfer of part of one State’s territory to another State; — the separation of part of one State’s territory and formation of one or more new States; or — the dissolution of a State and formation of two or more States. In the case of State separation or dissolution, although most individuals residing on the territory automatically become citizens of newly independent States when nationality legislation is adopted, large numbers can be left stateless. Migration movements before and at the time of independence as well as discrimination against marginalized ethnic and social groups may create particular risks of statelessness. The transfer of territory between States can have similar results. Therefore, it is vital to promote co-operation between the authorities of the (future) States concerned and advocate for the adoption of agreements and legislation to avoid statelessness, for instance, by granting nationality based on residence on the territory affected. The concerned States shall put in place appropriate measures to prevent statelessness situations from arising as a result of State succession and take action to address such situations.90 Article 10 of the 1961 Convention contains specific obligations in this respect: 1. Every treaty between Contracting States providing for the transfer of territory shall include provisions designed to secure that no person shall become stateless as a result of the transfer. A Contracting State shall use its best endeavours to secure that any such treaty made by it with a State which is not a Party to this Convention includes such provisions. 2. In the absence of such provisions a Contracting State to which territory is transferred or which otherwise acquires territory shall confer its nationality 64