Jolie first witnessed the effects of a humanitarian crisis while filming "Lara Croft: Tomb Raider" (2001) in war-torn Cambodia, an experience she later credited with having brought her a greater understanding of the world. Upon her return home, Jolie contacted the United Nations High Commissioner for Refugees (UNHCR) for information on international trouble spots. To learn more about the conditions in these areas, she began visiting refugee camps around the world. In February 2001, she went on her first field visit, an 18-day mission to Sierra Leone and Tanzania; she later expressed her shock at what she had witnessed.