Colonial boundaries were often arbitrarily fixed, as great powers claimed territories, conquered new possessions from old claimants, traded or sold outposts, and drew lines across maps of distant domains from the security of European capitals. In some cases, they disputed territories; sovereignty over uninhabited Clipperton in the eastern Pacific, to which both France and Mexico claimed rights, was not decided until the early 1930s. Similarly, not until the early twentieth century was Denmark's sovereignty confirmed over a portion of Greenland claimed by Norway. Even at the time of decolonisation, many frontiers remained so arbitrary that the United Nations, fearing chaos if attempts were made to redraw maps, stated that the borders of newly independent states should conform to old colonial boundaries. That principle did not stop numerous secession movements, civil wars and military conflicts between nations trying to gain or regain territories they considered rightfully their own. The United Nations also asserted that the interests of local populations should be taken into account and rights to self-determination recognised in decolonisation or cession, principles which sometimes clashed with that of territorial integrity.

Contemporary overseas territories have not been immune to disputes between rival claimants. In the Indian Ocean, for instance, the Comoros claims the French-administered island of Mayotte; France, the Comoros and Madagascar all claim the lies Eparses in the Mozambique Channel; Mauritius disputes France's claim to the Tromelin reef and claims the British Indian Ocean Territory.