April 1978 Nur Mohammed Taraki seizes power and tries to establish a communist state supported by the Soviet Union.

August 1978 Three thousand Afghan refugees flee to Pakistan.

October 1979 More than 20,000 refugees are in Pakistan. The United Nations High Commissioner For Refugees opens its first office in Islamabad.

December 1979 Soviet troops invade Afghanistan and 600,000 flee to Pakistan.

1980s Refugee camps in Pakistan serve as bases for militant Islamic groups, supported by the U.S. and allies to fight the Soviet occupation of Afghanistan. Between 1982 and 1991, the U.S. gives $2 billion in support of these opposition camps. In 1984, 1986 and 1987, cross-border attacks between Afghanistan and refugee forces in Pakistan kill many refugees.

1986 Pakistan government rounds up 50,000 Afghans living in Peshawar and sends them to refugee camps.

1989 Soviet forces withdraw from Afghanistan.

1990 About 6.3 million Afghan refugees are living in Pakistan, Iran and other neighboring countries.

1992 As the fighting settles, 1.6 million refugees repatriate.

1994 Taliban emerges and seizes most of the country.

June 2000 Heavy fighting between Taliban forces and the Northern Alliance and severe drought in Afghanistan drive 170,000 refugees to Pakistan by the end of the year.

Oct. 7, 2001 U.S. military strikes against the Taliban in retaliation for the Sept. 11 attacks against the U.S. provoke a new exodus. Pakistan closes its borders to all but the neediest. Click here for a look at where refugees fled prior to the start of U.S.-led air strikes.

May 1, 2003 Seeking to reassure jittery allies that Afghanistan is safe for reconstruction, U.S. Defense Secretary Donald H. Rumsfeld declares that major combat operations there are over.