Eritrea was once part of Ethiopia, but began a struggle for independence in the 1960s and finally became established as a separate country in 1993. The civil war that preceded the separation lasted for approximately 30 years, beginning while Eritrea was still considered part of Ethiopia and continued until 2000, even after independence was granted. Three waves of migration from Eritrea to the US occurred in the 1980s and 1990s, as refugees escaped the violent civil war, finding safety in refugee camps in surrounding countries, and then more recently as individuals (mostly men) sought to escape the mandatory national service. Despite the peace treaty with Ethiopia signed in 2000, there has been escalating tension along the border, along with discrimination against evangelical Christians and ethnic minority groups. The most common ethnic group in Eritrea is Tigrean.