No specific question today, just a request for some guided reading as I cannot for the life of me find any maps, books, or papers describing Mesoamerica at the end of the 14th century.
The period you are asking about, roughly the middle Postclassic, was a transitional period, and thus the dearth of material is not entirely surprising. Roughly, the history of the Basin of Mexico from the fall of Teotihuacan goes something like this:
So what you are really asking about is the Tepanec empire based at Azcapotzalco. Even more specifically, you want to know about the reign of Tezozomoc, the ruler of that polity who supposedly lived more than 100 years and in his decades of rule took Azcapotzalco from one of many Chichimec settlements to the dominant power in the Basin.
Unfortunately, the transitory nature and brief dominance of the Tepanecs leaves some difficulties in investigation. There are no surviving documents from this period. This is not to say that there are no records of this time, the Codex Xolotl and Mapa Quinatzin, for instance, portray the arrival and rule of the legendary Chichimec ruler Xolotl, and the subsequent ruling dynasty of the Aculhua, respectively. These works, however, are from the early 16th century, and form a corpus of literature preserved and interpreted by a descendant of Quinatzin, Fernando de Alva Ixtlilxochitl.
Alva Ixtlilxochitl wrote extensively about the history of his own family, and the history of the pre-Aztec Basin by extension, in the early colonial period. Of particular interest to you might be his Historia de la Nacion Chichimeca, whose early chapters focus on the arrival and settlement of the Chichimec peoples into the Basin of Mexico. As Alva Ixtlilxochitl was writing from an Aculhua perspective and with an eye towards justifying Aculhua land/tribute claims in Colonial courts, the writing is focused on the eastern lakeshore and heavy on genealogy.
Nevertheless, Alva Ixtlilxochitl's works remain some of the most important writings on this period, though his bias and accuracy have long been debated. Lee and Brokaw, for instance, have edited two volumes which cover this topic, and by extension the pre-Aztec history of the Basin: Texcoco: Prehispanic and Colonial Perspectives and Fernando de Alva Ixtlilxochitl and His Legacy.
Note that I've been talking about the Aculhua and the eastern lakeshore, not the Tepanecs, whose base of power was on the western/southwestern shore. That's in no small part because the defeat of Azcapotzalco left the Tepanecs as a minor power in the region. The Tepanec polity of Tlacopan joined Tenochtitlan and Texcoco in overthrowing the tyranny of Tezozomoc's successor, Maxtla, but are ultimately remembered (if they are remembered at all) as being the partner in the Triple Alliance that received 1/5 of the tribute, compared the the 2/5s received by the other members. I will elide here over the debate over whether this 2-2-1 distribution even actually existed to reiterate that no one cares about Tlacopan. By the time the Spanish arrived, Tlacopan appeared to be little more than an appendage of the metropolis of Tenochtitlan, and if you want to really enter into a disturbing void of historical research, try researching poor forgotten Tlacopan (or Tacuba, as it is often called, for reasons I have been unable to discern).
Tezozomoc had conquered the Aculhua, but the fact of their resurgence and participation in the Aztec Triple Alliance meant they were in a position to have their own history preserved and retold. Understandably, the Aztecs were no interested in promoting the glorious history of the empire of Azcapotzalco, and the polity mostly is remembered through works like Duran's History of the Indies of New Spain, which firmly paints them as the villain in the epic story of Mexica dominance.
Our prolific friend Alva Ixtlilxochitl is connected, however, to a text associated with the western Basin. His name is sometimes floated as the author, or compiler, or maybe just the copyist of the Codex Chimalpopoca. This work actually comprises three different works, the most important to your question being the "Annals of Cuauhtitlan" which, similar to the Historia de la Nacion Chichimeca, recounts the the history of the Basin from the Toltecs up through the Aztec imperial period, though this time with a focus on the polity of Cuauhtitlan. It is also heavy on the genealogy, but may be more accessible given that an English translation from Bierhorst exists.
Then there is Chalco, over in the southeast of the Basin, which has its own historical corpus via Chimalpahin. Like with his contemporary, Alva Ixtlilxochitl, Chimalpahin was writing in the colonial era, but largely drawing upon a pre-existing tradition and works. I've actually had a lovely back and forth with /u/drylaw on the topic of the pre-Aztec history of Chalco, so I'll link you over to that rather than repeating myself.
Bottom line though, is that the history of the Basin prior to the formation of the Aztec Triple Alliance is largely one of some chaotic demographic shifts culminating in one polity briefly becoming ascendant before being overthrown. The political regime that followed had no interest in preserving that legacy, so instead we get histories from either the a Triple Alliance perspective (Alva Ixtlilxochitl, Codex Chimalpopoca, various works detailing the Mexica migration) or from another major player in the region (Chimalpahin).
EDIT: I forgot about Davies' The Toltec Heritage, which focuses on Basin history after the fall of Tula. I cannot find my copy right now, but my recollection is that he spends a bit too much time building up the Toltec legacy as the prime mover of all political and religious decisions made, and spending far too much time on Culhuacan, but is otherwise an valuable (if dated) look at the time period.