Bazan
A Spanish surname whose exact origin is uncertain, but which likely arose as a regional or altered form of an older place-name or nickname.
The #4,388 most common surname in the United States (2010 Census) — about 1 in every 38,098 Americans shares it.
Etymology
The historical evidence here is thin and indirect. The excerpt you provided treats Bazan as an example of sound change from an older form, but it does not give a secure derivation or literal meaning. In practice, Bazan is best treated as a Spanish surname of uncertain origin, possibly connected to a place-name or to a phonetic alteration of an earlier surname form.
History
Bazan is found in Spanish-speaking areas and later appears in the Americas through migration. Because the available source is only an incidental mention, there is no solid basis here for a more specific historical story. The surname is relatively uncommon in the United States compared with major Spanish surnames.
Origin
Regions
Variant spellings
Fun fact
The excerpt cites Bazan as one of several examples used to illustrate consonant change in Spanish surname forms.
From the historical record
“según el origen Zerallvs, y según la vulgar ortografía Zeha- lios. )) Confirman la permutación fonética de st en z varios otros casos : Stuñiga. Zúniga; Basti, Baza ; Bastan Bazan; Bosimediano, i?<?r;«^¿í¿/7/ií) (no Vozuiediano, como se ^'iene escribiendo pueblo y apellido con ofensa de la más vulgar concordancia …”
— Ensayo histórico etimológico filológico sobre los apellidos castellanos