It is known as the world's largest refugee camp and is home to more than 400,000 Somali refugees. Most came to Dadaab more than 20 years ago. Among the Dadaab population is Siyad Mohamed. He was born and grew up in the camp. But his life there could soon be over. The governments of Kenya and Somalia and the UNHCR have decided that it is time for Mohamed and other refugees to go back to Somalia.