Another of the South American regions that fell to conquerors in the 1500s, Colombia was part of the Spanish Viceroyalty of Peru till the mid-18th century when it became part of a new viceroyalty encompassing what is now Colombia, Ecuador, Panama, and Venezuela. In 1810, the region achieved independence from Spain but it would not be until 1886 that Colombia was made a single republic. As in much of the world, the depression of 1929 augured serious economic and political problems for the country and a civil war broke out in 1930. In 1934, President Alfonso Lopez Pumarejo put forth a plan for reform known as "Revolution on the March." In the decade between 1948 and 1957, 'La Violencia' erupted, leading to the deaths of hundreds of thousands of Colombians. The 1957 plan that ended the violence laid out the provisions for power-sharing between the warring Conservative and Liberal parties. This system came to be weakened with the rise of terrorist and other groups -- both left and right -- that challenged the two-party arrangement. Fighting the mushrooming drug trade has taken center stage in Colombia for decades and with it, violence against the government, the military, and civilians.