After the conquest of the Aztec empire, the Spanish re-administered the land and expanded their own empire beyond the former boundaries of the Aztec, adding more territory to the Mexican sphere of influence which remained under the Spanish Crown for 300 years. Cultural diffusion and intermixing among the Amerindian populations with the European created the modern Mexican identity which is a mixture of regional indigenous and European cultures that evolved into a national culture during the Spanish period. This new identity was defined as "Mexican" shortly after the Mexican War of Independence and was more invigorated and developed after the Mexican Revolution when the Constitution of 1917 officially established Mexico as an indivisible pluricultural nation founded on its indigenous roots.