I'm from México and I really like the aztec civilization. This is a little guide on how aztecs used to name places. I'm not an expert in nahua, but this is something of what I know. By no means this is a complete guide and the rules can differ in some cases. Examples are the original word of real places, it could be different from today names.
Toponymies are formed by a noun and a prefix or suffix:
Select a noun, remove the –tl, –tli or -lli, add a suffix.
If monosyllabic, the accent of the word is always in the last syllable. Except co, wich is in the penultimate syllable.
In polysyllabics, the accent of the word is in the penultimate syllable. Except apan, wich is in the last syllable.
can/ca - place (Coyohuacan, place of those who workship the coyote)
tlan - land/city (Aztlan, city of cranes)
pan – in, at (Acapan, at the reeds)
co – in, where (Mexico, where Mexictli is [workshiped])
calco - house (Xochicalco, house of flowers)
puzalco – height, hill (Azcapuzalco, anthill)
ixco - infront (Cuautlixco, infront the eagles)
nepantla – in the middle (Tlalnepantla, in the middle of the earth)
apan – river (Papaloapan, river of butterflies)
tepetl/tepec - mountain (Chapultepec, mountain of crickets)
Select a prefix and add a noun, the accent remains in the strong syllable of the noun.
If the noun ends in –lli, remove the two last letters.
ixtla plain (Ixtlazihuatl, plain with the shape of woman)
example NOUNS (Accents are in caps)
Acatl – reed
CIhuatl – woman
chalchiHUItl - emerald
chiMAlli - shield
COAtl - snake
COyotl – coyote
cuAUtl – eagle
cuaHUItl – wood, tree
eHEcatl – wind
huiTZIlli - hummingbird
MIztli – small procionidae
Ometl – dawn
oCElotl – jaguar
oCOtl – pine-tree
queTZAlli – feather, also used as limpid, bright
TEotl – god (plural, teTEo)
TEtl – stone
TLANtli – fang
TOCHtli – rabbit
XOchitl – flower
yoAlli - night
YOlotl - heart
To denote ownership, workship or being holder:
hua (Teteohuacan, place of those with the gods)
Place this before the suffix or after the prefix.
pul (Acapulco, where big reeds grow)
Place this after the noun, if it’s the last syllable, use pulli instead.
To name the inhabitants from one place:
If the word ends in -tlan, remove the suffix and add TEcatl (plural, TEca). Ex. Azteca, from aztlán, Guatemalteca, from Guatemallan.
If the word ends in -can or –pan, remove the last n and add NEcatl (plural, NEca). Ex. Tlalpaneca, from Tlalpan.
Hope all this it's understandable.