Age of Empires Series Wiki

Military units from native settlements have their attack and hitpoints greatly increased.
—In-game description

Legendary Native Warriors (Exalted Natives for Asian civilizations) is a technology in Age of Empires III that can be researched in the Capitol by European civilizations and Mexicans or State Capitol by the United States or the Town Center by Native American and Asian civilizations once the Imperial Age is reached. Once researched, it upgrades native warriors to the Legendary/Exalted/Imperial level, increasing their hit points and attack by 50%, and for Somali Darood Militia increasing their ranged attack range by 2. Unlike native units' Elite/Disciplined/Veteran and Champion/Honored/Royal Guard upgrades, this technology costs food and wood.

For African civilizations, Legendary Native Warriors is researched automatically upon reaching the Imperial Age.

Before the Definitive Edition, if Legendary Native Warriors/Exalted Natives is researched before the native warriors' Elite/Disciplined and/or Champion/Honored upgrades at the Trading Post, they will have lower hit points and attack. Researching the earlier upgrades will improve them, but they'll be considered to be upgraded to the corresponding level(s), although this does not affect their gameplay. This has been patched since the Definitive Edition.

Choosing José Bonifacio to revolt grants Legendary Native Warriors and ships 20 Tupi Blackwood Archers as well.

Capitol technologies
Blockade · Spies · Knighthood · Peerage · Legendary Native Warriors · Immigrants · Large Scale Agriculture · Deforestation · Excessive Taxation · Cadets · Brigadier General
State Capitol technologies
Age III tech tree aoe3
Oregon Trail · State Constitutions · Statehood
Age IV tech tree aoe 3
Cadets · New Mexico Immigration
Imperial Age
Blockade · Spies · Brigadier General · Legendary Native Warriors · Iowa Farmlands · Pine Tree State · Mountain State Gold Rush
Other civilization's counterparts
AfricanLarge Scale Farming · Ebony Exports · Strangers' Quarters
AsianMechanized Rice Cultivation · Tropical Timber Trade · Collective Economy · Exalted Natives
Native AmericanLarge Scale Gathering · Deforestation · Excessive Tribute · Legendary Native Warriors