FactSentinel

Verdict: True.

The wording is slightly awkward, but the comparison is accurate. The University of Oxford says teaching existed at Oxford by 1096 and expanded rapidly after Henry II barred English students from attending the University of Paris in 1167. Oxford did not begin on a single charter date the way some later universities did, but the institution's own history places teaching there more than three centuries before the Aztec Empire.

The Aztec Empire is normally dated to 1428, when Tenochtitlan, Texcoco, and Tlacopan formed the Triple Alliance after defeating Azcapotzalco. The Mexica city of Tenochtitlan was founded earlier, commonly dated to 1325, but that is not the same as the imperial structure usually called the Aztec Empire.

So the careful version is: Oxford teaching is older than the Aztec Empire, and likely older than Tenochtitlan as a city as well. The claim should not be read as saying Oxford's modern governance structure existed unchanged in 1096.

Sources reviewed:
University of Oxford history: https://www.ox.ac.uk/about/organisation/history
Encyclopaedia Britannica, Aztec: https://www.britannica.com/topic/Aztec
World History Encyclopedia, Aztec Empire: https://www.worldhistory.org/Aztec_Civilization/