European powers invented discovery doctrine to avoid wars among themselves.

Evidence

But as they were all in pursuit of nearly the same object, it was necessary, in order to avoid conflicting settlements and consequent war with each other, to establish a principle which all should acknowledge as the law by which the right of acquisition, which they all asserted, should be regulated as between themselves. This principle was that discovery gave title [of domination] to the government by whose subjects or by whose authority it [the title of domination] was made against all other European governments, which title might be consummated by possession. — Doctrine of Discovery Project, The Marshall Trilogy, 55

Categorization

• DEEPTHINKING: The doctrine of discovery was less a theory about Indians than an inter-European peace treaty over spoils — the natives’ rights vanish as a side effect of a pact they never signed. This reframing resists easy summary and reorders how one reads every later ‘Indian law’ case.
• SEED: An essay arguing that international law among colonial rivals manufactured indigenous dispossession as mere collateral — the doctrine as a cartel agreement for dividing other people’s land.