Who was Itzcoatl?

Itzcoatl (Itzcōhuātl), "Obsidian Serpent", (1380–1440) was the first Emperor of the Aztec Empire. ruling from 1427 (or 1428) to 1440, the period Mexico threw off the domination of the Tepanecs and laid the foundations for the eventual Aztec Empire.

Elected as the fourth king of Tenochtitlan when his predecessor, his nephew Chimalpopoca, was killed by Maxtla of Azcapotzalco. He allied with Nezahualcoyotl of Texcoco, and went on to defeat Maxtla and end the Tepanec domination of central Mexico.

After this victory, Itzcoatl, Nezahualcoyotl, and Totoquilhuaztli, king of Tlacopan, forged what became known as the Aztec Triple Alliance, forming the basis of the eventual Aztec Empire and he became the first Emperor.

Itzcoatl next turned his attention to the chinampas on the south shores of Lakes Xochimilco and Chalco. Fresh water springs lining these shores had allowed the development of extensive raised gardens, or chinampas, set on the shallow lake floors. Successful campaigns against Xochimilco (1430), Mixquic (1432), Cuitlahuac (1433), and Tezompa would secure agricultural resources for Tenochtitlan and, along with the conquest of Culhuacan and Coyoacán, would cement the Triple Alliance's control over the southern half of the Valley of Mexico.

During his reign he constructed temples, roads, and a causeway was built. He established the religious and governmental hierarchy that was assumed by his nephew Moctezuma I upon his death in 1440.