Since about half of all Somalis are nomadic or semi-nomadic, there are substantial movements back and forth across the frontiers in the normal range of grazing activities. Within the country there has been a gradual migration toward the south and southwest, especially since the north was drought-stricken in the 1970s and early 1980s. A campaign of political terror began in 1986. So severe were the effects that it was estimated in 1993 that three-quarters of the population had been internally displaced since 1988.
The conflict with Ethiopia led to the influx of many refugees from the Ogaden, most of them ethnic Somalis. In 1990, an estimated 586,000 were being assisted by the UN High Commissioner for Refugees in refugee camps. The government claimed the total number in refugee camps exceeded 1.3 million. Yet the political violence in Somalia was so extreme that about 600,000 people fled the country between 1988 and 1991.
After Siyad Barre's regime fell in January 1991, fighting began between 16 different rival factions in Somalia. These clan wars and the long drought led to over 900,000 Somalis fleeing to neighboring nations. Of these, some 400,000 went to Kenya. Due to UNHCR's aid program that was started in 1992, a majority of these refugees have returned. However, UNHCR's repatriation program was broken off in 1995 due to fighting. As of May 1997, there were still 285,000 Somali refugees in Ethiopia, 131,000 in Kenya, 20,000 in Djibouti, and 10,000 in Yemen. In 2000, the net migration rate was 1.7 migrants per 1,000 population. This was a significant drop from -21.9 per 1,000 in 1990. The total number of migrants living in Somalia in 2000 was estimated at 22,000. The government views the migration levels as satisfactory.