The first Geneva Convention was in 1864. The more recent Geneva Convention, announced on 12th August 1949, is mapped here. This convention demands the protection and respect of individuals who do not (and sometimes cannot) take part in hostilities. This is an important part of international humanitarian law.
Unsurprisingly Switzerland was the first to ratify the convention in March 1950 - Geneva being a Swiss city. Other signatories that year were Monaco, Liechtenstein, Chile and India. By 2004 all territories mapped here were signatories (or the territory claiming sovereignty over them was).