Complex sentence: But in 1916, during World War I, the Portuguese occupied it, and after the war the Treaty of Versailles defined the border as running along the Rovuma, thus allotting the triangle to Mozambique.
Split into simpler sentences: But in 1916, during World War I, the Portuguese occupied it. After the war, the Treaty of Versailles defined the border as running along the Rovuma, thus allotting the triangle to Mozambique.