Vietnam has a long history of foreign intervention.  At one point it was part of China and called Annum.  Then, around 1860, Europeans arrived from the Netherlands and France and by 1885 France controlled the region as a colonial territory after France defeated China in the Sino-French War of 1885.  

From 1885-1954, Vietnam led the independence movement against France and finally defeating the French at the Battle of Dien Bien Phu.  The Geneva Conference of 1954 finally provided the independence of Cambodia and Laos but Vietnam was split at the 17th parallel.  

The French withdrew by the end of 1954 leaving a Vietnam split between the communist forces of the North and the non-communists of the South.